First BMW, pitfalls and tips?

[DankDeathPunch]

To make a long story short i am looking for a BMW.
And i have my eyes set on 1, 3 or 5.

What model should i go with?
What are some common problems with them?
As a sidenote i am in europe so need to factor in rust etc...

I am just looking for a reliable and nice daily driver that still has some power in it.

Currently looking at 2000 - 2008 models due to the price.

Thanks in advance!