With a good instructor you can learn to fly on a pattern airplane. It's not as easy, though. Ask your instructor's advice on what he would be most comfortable teaching you on. I've been flying for over 30 years now and I still like to occasionally fly the trainer I learned on. Yep, it's still in one piece. So don't worry about investing in a trainer. If you don't want to keep it after you have some experience, it should be easy enough to sell to another newcomer. Good luck with whatever you decide.