If you specifically want old, I'd suggest at least going good, and the beauty is it's affordable these days.
The Nikon D2x is actually quite a good camera. It was Nikon's first attempt at a CMOS sensor. It sort of falls apart at high ISO, but at 100-400 it can give quite clean results.
No one I'm aware of is making CCD based cameras anymore for good reason, but they do have some interesting features. The Nikon D1 series actually have flash sync at any speed because of how the CCD is operated at high shutter speeds. Weirdly enough, in the 2020s, I've found the D1H the least reliable of the bunch. The orginal D1s tend to work well in my experience but they are clunky. The D1x is a good option and it has a 6mp sensor with an interesting arrangement that many people back in the day would interpolate up to ~10mp or so. The biggest problem with all of these cameras is that the batteries weren't great when they were new, and are often awful now.
For something of a classic, I might suggest a Nikon D100. This was one of the first consumer-class DSLRs(although a $2000 camera when new) and has a decent 6mp CCD. The biggest weakness I seem to run into with them is that the mode dial, which was pulled straight off the N80 film camera but needs to be moved any time you want to change ISO, sometimes gets touchy. The D70/D70s are newer cameras that are improved in a lot of ways but IIRC have the same 6mp sensor. Choosing between them, I'd get a D70s for the better screen. When I was jumping ship to Nikon and decided I'd go all in, the D70s was the first Nikon DSLR I bought(used it for about a month before I bought a D2x and then went in big with a D800) so it is a sentimental favorite for me. The D100 and I think the D70 use the EN-EL3 battery. The D70s uses the EN-EL3e, which is backward compatible with the EN-EL3 and was used in a pile of different very popular Nikon cameras through the 2000s(D200, D300, D700, D80, D90).
For something different, I still like the Fuji DSLRs, which are Nikon mount. Back in the day, all the makers were trying all kinds of tricks to squeeze more resolution out of relatively large pixels and also improve dynamic range(a real weakness of CCDs). Fuji's answer was the "Super CCD" which used a honeycomb array of photosites, and even more interestingly had two pixels(called the R and S pixels) per photosite. The first gen(S1 and S2) had 3 million photosites and the second gen(S3 and S5) had 6 million photosites. Of these, I'd completely avoid the S1 and S2. Both are very much "digital camera stuck into a film body" cameras, and you actually have to keep CR123a batteries in them to operate the camera functions as well as AAs to operate the digital functions. The S2 can run off just the AAs, but nearly all of them today have dead sensors. The S3 integrated things a bit better, but is still slow and clunk to use. It is meant to run on NiMH AAs, and can use any that you buy today, but will chew through them like crazy. The S5 is D200 body with a Fuji sensor and electronics, and actually operates like a modern DSLR. The big catch with it is that even though the batteries are Nikon EN-EL3es, they have Fuji-specific firmware in them and the S5 will refuse to work with anything that's not a Fuji battery. The camera will power up but refuse to do anything other than tell you invalid battery(Nikons will gladly use the Fuji batteries). I've had good luck with aftermarket ones out there for it, and most of the originals that I find are still good.
I've had several Kodak DSLRs, all in Nikon mount, although many models also were made in Canon mount. They are interesting and many pros loved them for their unique color rendering. The last of them, the DCS 14/n, was the first Nikon mount camera with a 24x36mm sensor, but that was about its only upside. From my observation, though, Kodaks are also some of the only truly collectible early DSLRs and you will pay dearly for them.
All of the above are capable of outputting JPEG files that can be read by any computer. Apple RAW and Adobe RAW in 2022 are both still capable of reading the RAW file output of all of these. All of the cameras I've specifically mentioned use Compact Flash cards, but for most of them you need 2gb or smaller cards, so if you decide to get one be prepared to hunt. All of the Nikons other than the D1 series can be connected to your computer via a USB cable for file transfer(the D1s need firewire) or of course use a card reader.
