Fern - you're particularly invited to comment.
I'm in what is probably a common position hunting for a first DSLR in that I've had quite a bit of photography experience in the past, and through my use of digital compacts etc have a good idea of what I want without having actually tried it. This makes it more complicated in some ways, because I won't be happy to do the noob thing of just buying whatever random outfit the salesman thinks is good/has the best margins/most likely to require quick upgrading and then finding out how it all works and what compromises I can't live with.
The issues about which DSLRs currently live or die for me (apart from cost) pretty much in order:
Low sensor noise at high ISO
Good colour control and presentation
A great viewfinder
Fast and controllable focusing
Articulating rear screen
Easy manipulation of both shutter speed and aperture manually
I'm not fussed about sensor resolution as long as the sensor is about 12MP or more, but noise is a really big deal for me and has already reduced the desirability of some otherwise highly competent cameras. I've been searching back through DPReview.com looking at older high-end models, and many of them, particularly in the 2006-2010 period, were showing up with densely packed sensors that were noisy at ISO800 and poor at ISO1600 and above. There have been a few cameras at the budget end, including the Sony a58 and Pentax K500 that don't have the highest resolution, but do have extremely impressive noise control, and would be quite usable at ISO3200 to ISO6400. Many Nikons within my reach do not seem to have noise well controlled at higher speeds.
At a single blow the issue of colour presentation removed Canon cameras from the equation. Canon have an almost trademark color filtration, and while I've seen some utterly superb images created using Canons, the failure of many of the more affordable models to handle shades of red and subtle tones well made it easier just to stop looking. There's also the issue that I don't find Canon bodies intuitive to use, and they all require the motors and image stabilisation built into the lens too, which pushes the price of glass up.....
The viewfinder design has had me slightly running round in circles, even though it may be a red herring. The camera I favour - Sony's a58 - has an electronic view finder (EVF) rather than a standard optical viewfinder, and this is a real double edged sword. The downside is that it can be a little small and dark, doesn't always track moving objects smoothly and may not provide the best focusing information. The upside is that you get true live view, and can see the effect of exposure compensation effects (and sometimes depth of field with aperture adjustment) while you're looking through the camera. This is where the connection with my use of digital compacts it strong, because I would pretty much always adjust exposure on the screen before capturing an image, giving me effectively manual exposure control, even in program mode. The idea of going back to shooting images 'in the dark' and the reviewing them afterward for exposure seems completely daft - you might as well get a light meter out and stand in front of your subject (I still have your old Sekonic, Phil, if you read this!).
OTOH the Pentax K500 has what is reputedly a large and bright OVF giving almost 100% coverage, and that is VERY tempting.
Fast and controllable focusing is a given with a modern camera, isn't it? Well I normally use spot focussing, and on the Samsung this works well. The Fuji however was another story, and it would make it's own choices about what to focus on if you were trying for macro or shooting through glass. It should be less of an issue with an SLR since one can switch to manual. However one thing that really impressed me with the old Sony a700 body I tried earlier in the week was the eye level activated focus mode that would automatically focus on the target when you raised it to your eye - no more missed shots while trying to carefully half-press the shutter button, check it was in focus before fully pressing. That feature would have probably doubled or better the number of successful bird shots I've captured.
A fly in the focusing ointment is that the a58 I favour has been reported as suffering back focusing (focusing behind the target) sometimes, and Sony will not fix this because the cameras are within manufacturing tolerance. This is not unique to these cameras, and the Fuji I sold certainly did this, as does (did?) the Canon SX40 my brother owned.
Many cameras do not have a screen that comes out from the body, and I'm torn as to whether this should be a show-stopper. It always seemed silly to me - it's for people to take selfies, right? Until I got down on hands and knees to take a macro shot and then discovered I wouldn't need yoga to look through the viewfinder or compose on the rear screen. It's also useful if you photograph groups of people, because it allows you to work like a professional, mounting the camera on a tripod, making proper eye contact as you move them around and check composition by glancing down like I did with my roll film cameras. Many Sony cameras have articulating rear screens, and most others do not.
And then there's the rest, which are somewhat related.
In my 20s I'd happily carry 8-10kg of photo gear around all day, but now my shoulder aches after 30min with a bag foll of 35mm gear. So I loved the size and handling of the a700 I tried Monday, but was worried about wearing the 900g (+ lens) mass round my neck. Modern entry-mid range cameras are nice & light, being mostly polycarbonate, and come in around 500-700g, plus modern lenses are also placky and likewise relatively featherweight. A friend recently bought a Nikon D3200 as her first DSLR and has been taking great pictures, but the body is tiny in my hands, and would feel cramped, I think, so something a little larger is required. It would also be great to have separate input dials for aperture and shutter control when in manual mode, but most entry/mid level bodies use just one, the exception being the Pentax K500.
So here's the rub: I have a bunch of old and heavy minolta lenses that would give me 'instant outfit' with a Sony a58, and that camera ticks most of the boxes, yet it isn't flawless by any means, and there are serious questions about viewfinder quality and focusing. These are very cheap right now in relative terms.
The Pentax K500 also ticks many boxes - on paper, hope to try one soon - in different ways from the Sony, and comes with a quite different set of trade offs. It also has image stabilisation inside the body like the Sony, and can take old Pentax lenses with varying degrees of functionality as long as they have a K mount, which opens up a huge range of glass. It also has built-in HDR functionality and a bunch of other desirable program features. And IF I want to change makers, now is the time to do it. But some things are clunky or poorly designed, like the live view and video functions, and it would require buying further lenses.
It's nice to have a new camera with clean sensor and warranty.
Or I could sacrifice a couple of those 'wants' for an older pro/upper mid-level model, with greater robustness, more function control and lower image quality and risk buying something that was too heavy to want to carry all day and left me frustrated about noise or blur.
Choices aren't an unmixed blessing, what ever the Tory party might think.
Let me tell you, looking at camera adverts and reading reviews becomes TEDIOUS after a bit. I know more about the development of various camera lines than I ever wanted to, who uses whose sensors and which lenses to buy. Frankly it's making stuff fall off the back of my mental desk. Think I'm going to just take a best guess & do it to stop the fuss - as someone said, there's no bad cameras at this level being made now.
Lets see if I can negotiate a discount with LCE in Leamington tomorrow.