if you already have an apple desktop or another laptop i would say MBA. If this will be your only computer than there is no question, buy the MBP. Another option is to but a mac mini and a MBA. If you really want portability thats they way to go. Whatever you buy make sure to wait till after the WWDC. Somethjing might get updated and the Education discount starts June 5th.
The consensus is either the MB or MBP is better - especially if you are keeping it for 4 years. I have a MBA and after owning both the MB or MBP, I prefer the MBA - although I do miss the real estate and processing power. I do have a Mac Pro on my desk to do my heavy lifting.
I am with the majority to say the MB or MBP is a better choice for college than the MBA, but if portability is the #1 reason for a laptop (which was mine), get the MBA. Good luck.
macbook pro because you want it to last 4 years. Even though everything sold today will seem outdated in 4 years, a macbook pro will hold up a lot better than a machine with a 1.6 ghz processor and integrated graphics.