Some useful comments and suggestions.
In the end though, I suppose it all depends on your budget & what Mark you are looking for.
If you want a good representation/selection of several marks for a good price, but are happy to put up with a few quirks & inaccuracies, then the JF/AH pack should suit you just fine. There aren't many repaints that have been released to my knowledge, but I know there are quite a few somewhere that could be.
The Real Air MKXIV still stands up very well after all these years, and represents good value for money. This is still a firm favourite of mine. Good FPS and a functional, crisp & clean VC although perhaps lacking on some of the finer details but you do have the neat option of removing the gunsight and having modern radios in its place instead, as per some today’s airworthy examples.
The WoP Spitfire MKI is a good one too (I believe the basic 3D model was the one used in Shockwaves BoB ‘Wings Of Victory’). Despite having quite a few niggling shape & detail inaccuracies (which the Shockwave team have gratefully acknowledged and might one day hopefully fix), the model is still up to the usual Shockwave high standard with a clean, crisp & FPS friendly model & textures, and a nicely detailed & functional virtual cockpit as you'd expect from them.
I'm surprised though that no one has mentioned the Plane Design Spitfire XVI.
http://www.plane-design.com/
Personally, this is the best out there in terms of 3D model accuracy and detail (the shape is bang on, and beats all other Spits payware or freeware hands down). The VC is as detailed as possible, with almost everything clickable or switchable (even if it has no function in FS) and has everything you'd find in an original MKXVI. The FM has at least tried to model some of the quirks of the real thing (such as adverse yaw, along with the gyro effects of the prop), which the others don't appear to have. In retrospect though, it's possible this was a step to far, as it seems these features fustrated a lot of those who bought it, and put a lot more off buying it. A real shame!
As you can see, they were working on the MKVIII, IX & PRXI (all of which I was lucky enough to get early stage models of), but it seems sadly development has dried up. I'm really hoping Ed and his team can restart work on them, as it would be criminal to let such work go to waste.
Hope this helps.
Cheers
Paul