I'm looking at a new car as I'm doing around 2k miles a month now and can't decide between the A4 and 320d, or even 330d to put a spanner in the works!

On my budget I have narrowed it down to:
Audi A4 (B8, 143ps) 58-09 plate, around 70-80k miles
or
320d/330d 07 plate, around 100/120k miles
I'm off to look at a few this weekend but wondered what you guys would go for? How are the maintenance costs on each? I like to work on my cars when i can too - I heard bmw's aren't to DIY friendly?
any advice/previous experience on either is greatly appreciated!