For school, go for mid range TI.
Simply because everyone is using it, and if you have a question, you can always ask another student or instructor, and they would know what to do.
Compare with all the graph calculators out there, TI is so-so.
If you are going to be an engineer, you might get another one down the road.
But as for school, TI is fine --you don't want to be left behind because no one knows (including you) how your calculator works
