depends how much money you want to spend... if you plan to mod the car at all, you're gonna need to replace the headgasket and that can get expensive. so if you're tight for cash get a 87-88 and save the leftover cash for head gasket and mods, its also far easier to find a 5spd in those years...
i personally would go for 89+, the minor updates between the years make them look cleaner. also you're more likely to find a 89+ with lower mileage, so the head gasket may still be good for awhile. but then again, if its 5spd you're after, it can be a pain to find one in 5spd + good condition
