330i/xi are top of the tree...
But for the price/power 325i/xi are pretty good. They share alot more "common" parts... where teh 330i/xi have a few more exotic parts.
The xi cars sit a lil higher because of the AWD suspension.
Go based on your budget...
$75 - $90 to fill a gas tank. (89 and 91 Octane)
$100 per oil change.
$2000 yearly maintenance for my 325i.
$3000 for yearly maintenance on a 330i/xi should be safe? (what do you think guys?)
Thats just for a 325i. (not saying its always gonna be those $$$, but you never know)
thats just my 2 cents.
If i had a choice, and found a good price... i would have probably got a 330i or 330xi personally. Knowing what i know now. :p