Out of your list it's hard to say...
If you are rules oriented you might like Civ Pro, memorize, memorize, memorize those statutes. Or as, my beloved Civ Pro 1 prof used to say, "See this blue book (The Federal Rules of Civil Procedure Supplement), open it, it won't bite."
If reasonableness is your game, Torts defaults to a reasonable person (as does Contracts.) Most of Torts seems to be based on common sense (And I said most of, not all.)
Do you miss the logic games on the LSAT, do you find yourself wishing you had a reason to figure out which day Sally eats meat and Fred eats Fish? Then you might like Property or you might like the future interests/remainders/crazy ways people leave things to their families in wills. The reverse is true if you aren't the type of person who likes A, B and C then the class will probably not be easy for you.
If you ask the right three people they will probably say three different things. It all depends on what kind of a learner they are and what kind of prof they had. But the truth is all of the classes are hard...law school is hard. Hopefully my description of the classes and the things you'll be learning will help you decide which one you feel will be the hardest for you.
Good luck with classes and congrats on starting law school!