iv got both
mk3 every time
thing is, buy a crap unloved mk 2, 3, 4 etc and it will have its problems
my mk4 was bought brand new and it has had alot of electrical issues, mostly wiring harness type problems, annoying stuff
my mk 3 was bought 4 year ago, didnt know its history or anything and cost peanuts really, and its never once let me down.. makes the mk4 look sh!t really

the mk4 is alot faster tho but its a derv with a remap, had a 1.8t Mk4 before that and it was slow, about as slow as my 8v mk 3, and before that i had a mk 4 2.0 and that was slow too, nice to drive just slow