Which is better a cannon xsi, nikon d90 or a sony slt-a33?

Nikon. While many Canon fans say that they are more "user friendly" Nikon is known for being more professional. You have to actually learn something to be successful at a Nikon, and thats exactly what i love about the Nikon family. I love the technical side of my artwork and would recommend it to anyone who wants to do it professionally. I personally shoot with a Nikon D200 and would recommend the D300 if you have the money for it. I understand your a student but the D300 is worth the money. Along with that, make sure you have a great lens, because thats extremely important as well. Good luck with your degree. God bless :)