Macbook Pro, without a doubt. People say, "Oh but the Macbook is far more portable" and whatnot but I really don't notice a big difference. In my opinion anyway, the differences are so negligible. The pros of the MBP outweigh the size of the MB. But then of course you have to consider price.
I'm still transferring data from my Powerbook to the Macbook and i'm sort of disappointed whenever I go back to it and see the difference in screen real estate. This is a 3 year old Powerbook, so the screen is very very dull compared to the MB!
Either way, you're still going to get a fantastic notebook. You should call into your local store or whatever and compare the screens with the apps you use most often etc.