The 8v is reliable and fun, the 16v is a bit more desirable as it has that bit extra power and it's slightly lower as standard, but they can vary wildly depending on if they've been modded, thrashed or looked after.
I think it's slightly easier to find an 8v GTi that is in good condition and not been thrashed than to find a good well maintained 16v.
But then if you're buying something that you know needs work as a project, then it's a different case.
If it's running and MOT'd (with plenty left), the seller will get whatever they can, but if it's either a non-runner or without MOT I wouldn't want to pay more than £500 for a Mk2, unless you have the MOT failure sheet and you know how much it'll cost to get running.
For example, I bought my Mk2 16v (G reg small bumper 3dr) for £750 and it supposedly had an MOT. But the seller had lost the certificate. So I took it to be MOT'd thinking it would pass, then was told it would need £300 worth of welding to the floorpan.
It also depends on what you want to do with it, mod it nicely or get it back to original spec, whether you will run it yourself or sell it on. If you modify heavily you'll never get all your money back when you sell it.
