I have driven each of these models.
the e30 is a nice car, fun to drive and keeps occupied on a rainy day.
the e36 a bit more refined, a little les tail happy. Although old she will sure as hell put out when you need her to. if you look at the M3 in this model, you will find that its like driving a 327iS but with a little more control
the e46 is an awesome car to drive. like Prado said, the 318i is one of those start up and go daily drives. Believe me, they go for years. they are quite economical for in town driving and even long distance. they are very comfy. if you want go for the bigger build engines and you can have fun too.
me and my very personal and humble opinion, I prefer the e36 M3 as it gives me the best of both worlds. she aint economical but who buys an M3 for economy. she is fun when you need it to be fun but she can be quite tame when driving decently. yes, you will need to put some work into her and quite a bit of elbow grease to get her back to her glory days but when she is there, you are set for a very long time.
the other thing my dad said to me when I was younger, choose your car like you choose your women.
e30 - older than you and a lot of fun when no one is looking, you don't really want to attract too much attention when they are around because although attractive, someone else may want in on your fun too:rollsmile:
E36 - about your age, a lot of fun and you don't really mind getting caught, fairly grounded and you kind of pick up what they want and they are very loyal

raise:
e46 - a little younger than you, fun but it comes at a price because everybody wants some, you want to get caught because it will be the talk of the town but she tends to milk your pocket and you may need deep pockets. BITCHES AINT LOYAL.. LOL:thumbdo:
ok, enough my crap.. :roflol::roflol::roflol::roflol:
dude, its ultimately what you want. go drive each of them. if need be, start with an E30, if you don't like it, flog it cause someone will want it.. and so on and so on
just enjoy it..
thank you :ty::ty::ty::ty: i'll be here all week