I use a pen and paper. Honestly, there's not that much you need to write down from class discussion. If you're going over the black letter law, you might as well fall asleep because that's all going to be in an E&E which won't explain the rule incorrectly (which professors DO do occasionally). Just write down stuff that is unique that the prof says. Policy stuff, or if you are in a Con Law class and have a prof who's interest is Federal Indian Law, then obviously make sure you know everything he wants you to know about that.