K-A's sentiments about the 3 vs 5 express many of my observations. I was inclined to be a 5 buyer at first, coming from a MBZ 300E, and used to mid size lux 6 banger. But when I hit the dealership and saw the F30s in person I said WTF! Began test driving 535s and fell in love with roomy cabin but drove 328 to compare. Couldn't fathom a 4 banger performing like that, and I owned a 16V 1984 MBZ 190E manual.
The F30 cabin looks like a cut and paste designed by committee job compared the the cabin of the F10 which appears finely crafted, fitted, and engineered, IMO. But I was sold on 4 cylinder and so apparently was BMW. They thought enough of it to power the 528i.
Long story short, I slowly shifted to favoring the 3 once I discovered the M Sport package available with the options I wanted. Bottom like is I'd be pleased to drive either.