looking for first bmw - which model to get?

i'm considering buying a used bmw. which models/years are most reliable? which should i avoid?

i just drove a friend's 06 530i that has been maintained well (kept in excellent condition too) but has almost 100k miles. he's asking 14.5k. i like the car, but wondering if that's too many miles.

i'm looking to spend less than 15k$. i'm coming from owning 2 subarus, a nissan sentra, and an old honda lol.