In the USA I think mode 2 is what nearly everyone flies. Some of the guys that learned on the old radio systems in the early years still fly mode 1. I believe that some competition flyers MIGHT still be flying mode 1 since it isolates the elevator and ailerons from being on the same stick.

I would fly what everyone around you flies if you are starting from scratch, its fun to share others planes, and your own, its also easier to help people if you fly the same mode.