DSLRBodies

I'll start with Nikon (Canon is below). There’s good news and there’s great news. 

The good news is that there isn’t really a dud amongst all of Nikon’s current DSLRs. The DX DSLRs are all equipped with near-state-of-the-art or state-of-the-art 20 or 24mp crop sensors and differ primarily on how features are brought forward to the user and how many of those features there are. The FX DSLRs come equipped with near-state-of-the-art sensors across the board, but with more variation in pixel count (16 to 45mp).

The great news is that several of Nikon’s DSLRs stand out from the rest, and are ones I can heartily recommend here in 2021:

• D850. The D800 was the best all-around DSLR back in 2012, and the 2014 D810 refresh made enough changes that many of us D800 shooters upgraded and were very happy we did. The D850 did that again. This latest D8xx version is faster, has more pixels, a better autofocus system, and is just a little more refined all the way round. The Live View issues are (mostly) solved. The 45mp sensor is about as good as it gets for those that want pixels over high ISO performance, not that it’s a slouch at higher ISO values, all else equal. As I update this article, there are only two DSLRs I haven’t used from any maker, and I’ll still stick my neck out and say that the D850 is still the best all-around DSLR here in 2021, just as the D800 was in 2012-2013, and the D810 in 2015-2016. Thom’s Review of the D850.
• D780. On paper it doesn’t look like a big change from the much older D750. In practice, it’s a lot different. Yes, the optional grip and internal flash were dropped, but pretty much everything else was refined and made better. The addition of phase detect on the image sensor means that the D780 acts like a mirrorless Z6 in Live View, which makes this the best Live View on a DSLR, bar none. Nikon did a solid job polishing up their workhorse camera. Thom’s Review of the D780.
• D7500. The DX crop sensor has its pluses and minuses. For most of you, the minus is that it’s about a stop removed from the D780 sensor, all else equal, though you can get that back with some clever lens choice (e.g. the Sigma 18-35mm f/1.8). The bits of banding deep in the shadows of the D7100 are gone, and the new sensor is very well behaved. The pixel density has dropped a bit from the D7200 but is still near perfect for the wildlife shooter. The constrained buffer of the D7100 is gone, and the D7500 also blows past the D7200 in this respect, plus we now have a 1.3x crop option. Unfortunately, the frame rate and build quality isn’t at the D500 level. That said, the D7500 is the best consumer DSLR Nikon has made, hands down, and it manages a very respectable 4K video, too. Thom’s Review of the D7500.
• D500. This is a mini-D5 with all the Nikon D5 technology at its core. A new, better autofocusing system, high performance cards and buffer support at 10 fps, an improved metering system, and built-in SnapBridge. Great additional user controls in a carbon fiber/magnesium body. The 20mp sensor is arguably the best DX-sized sensor currently made (particularly at higher ISO values), the viewfinder and tilting touchscreen LCD top notch and a specification above the other cameras. Thom’s Review of the D500
• The D6 is really an expensive choice that you need to need. The D500 has virtually everything the D6 has except for two things: an FX sensor, and the new improved autofocus system. The D6’s image sensor is highly tuned towards high ISO work, and the camera nets an additional 4 fps over the D500 in continuous shooting. Still, you pay a big premium for that, so you really have to need those specific things to justify buying a D6. That said, there's not a better DSLR for sports and some types of photojournalism.

As I hinted, I can (at least conditionally) recommend any of the current Nikon DSLRs. But if you’re not going to pick one of the above, you should note a few things about the other options (the conditional part):

• The D3500 and D5600 shoot Compressed NEF only. What that means is that highlight information is sacrificed to make for more compact files. Nikon calls this visually lossless, and it truly is as long as you’re not making huge post processing changes in the highlights. It’s not a deal breaker, but it’s less than optimal.
• The D3500 and D5600 have arbitrary feature reductions. With the exception of the swivel touch screen on the D5600, both these cameras remove features you’d find on the D7500, and sometimes controls (front command dial, for example). So run through the specifications list very carefully and make sure what you want is really there. Moreover, these two models changed so little I didn’t bother to create separate reviews for them. See my older reviews. Thom’s Review of the D3400, Thom’s Review of the D5500
• The D610 doesn’t need to be avoided, but old in feature set and focus system. The D600 dust/lubricant fiasco totally devalued the D6xx series in most people’s minds. Thus, you’ll find the D610 at ridiculously low prices as demand is low. As with the D3400 and D5600, you have to watch for arbitrary feature reductions (in the D610's case from the D750 and D810), but the D610 is a much more complete camera than those DX consumer DSLRs are to start with; the feature reduction is remarkably minimal. Thom’s Review of the D610
• The D750 is sort of like the D5600: a middle model. Nikon really wants you to buy the middle model in the DX and FX lineups. Note that both have desirable moveable rear LCD screens (the D750’s tilts up and down), something you usually don’t find on the other models below and above them. There’s nothing at all wrong with the D750. It’s a fine camera, and given it’s price differential, many of you will buy it over a D810. That said, the D810 was enough better than I rarely use my D750, and the D850 is even better. You buy a D750 these days because it’s a bargain for its performance. But it'll go away soon, I'm pretty sure. Thom’s Review of the D750
• The Df is a bit strange. The DSLR sibling that is the most different is the Df. It’s not just the retro controls, it’s the entire mix of features starting with the 16mp sensor and no video. You really have to want what’s in this package to buy it, I think. For those of you who manual focus through the viewfinder, the Df does have the best focus screen of the Nikon DSLRs, which tells you something about the intended audience. That said, there’s just a little too much Dr. Jekyl and Mr. Hyde to this camera’s personality. Nikon didn’t go all in with the retro-film-like-camera thing, nor did they remove all that much of the digital DSLR from it (it still has Live View, for instance). This makes it a bit of a “tweener” in design, and that shows in some of the control functions. However, this is the smallest of Nikon’s FX DSLRs and the sensor is wickedly good in low light, so coupled with a set of f/1.4 or f/1.8 primes, some folk will be very happy with this camera. The more you zoom, the more I’d suggest this isn’t the camera for you. Thom’s Review of the Df

Canon DSLRs

I have less experience with Canon DSLRs, particularly older models. Still, I've used most of the higher end Canon DSLRs for extended periods, thus believe I can make solid recommendations here.

In Canon's current lineup, I really only like and recommend three models:

• 1DX Mark III. This 20mp "speed" camera is the full frame sports photographer and photojournalist war horse, updated in 2020 with a number of state-of-the-art features and performance enhancements. It essentially has an infinite buffer, plus the focus system is Canon's best to date. I'd tend to put the 1DX Mark III just behind Nikon in terms of focus, but ahead of the 1DX Mark III in frame rate. 
• 5D Mark IV. While this full frame model is a bit long-in-the-tooth now—four years old—it's still a very solid camera. If you're sticking with DSLRs, it's probably Canon's best all-around DSLR ever. Not quite the pixel hound the D850 is, I find the 5D Mark IV produces very nice imagery.
• 90D. If you're thinking crop sensor camera to save some money (perhaps to be able to buy lenses), the only current Canon DSLR I'd consider is the 90D. It's not quite a 7D replacement, but it's close enough that some might consider it that way. The good news here is that the 90D uses Canon's new 33mp APS-C sensor, and it's a very good sensor. Because this isn't a high-priced camera, there are some compromises in body build and feature set, but I still find this to be a well-rounded DSLR.

Where I have problems with Canon's current DSLR lineup—and particularly so because there are excellent mirrorless options from Canon now—are these cameras:

• 6D Mark II. Up until the point that the mirrorless Canon RP came out with basically the same feature set and image sensor at a lower price (sometimes far lower), the 6D Mark II was an adequate full entry model I could conditionally recommend. Now? You're buying a dead end and spending more money on it than a lot of better alternatives (both from Canon as well as others). 
• 5DS and 5DSR. These early (2015) "megapixel monsters" (51mp) were basically a 5D Mark III body with a pixel count boost. Unfortunately, they didn't perform in a way that made that pixel boost particularly attractive. The current Nikon D850 simply has better pixel integrity than these cameras and their older technology image sensors. And you're more than a generation behind in Canon's UX/design when you buy one. 
• The entire Rebel lineup (Kiss in some countries). Even the SL3, which is the latest in the SL line I used to like, is looking very dated and cut down now. Some of the sensors in these models are really showing their age now, and Canon's habit of de-contenting the lower end models is annoying.
• 7D Mark II. I was surprised to see this was still "current" in Canon's lineup. When it came out, it was a good camera, though not up to the standard that the D500 eventually set. And that's the problem.