Having had leather seats in other cars it wouldn't be a preference of mine, not that I really care too much.
If you decide to go for a manual one, make sure you get a LONG test drive in it first. The pedals are offset to the right, and I found the clutch in my 125i to be utterly dreadful. It's a single-plate affair that has an inconsistent biting point, and sometimes shudders on pull off.
It would be worth test driving the auto even if you think you don't like them. The ZF 8HP box in these cars is a very, very good.