You should see movies 4-10 those are the best, even if they aren't canon to me they are the best anime TV series movies ever! I don't know about this 3D stuff, I'm hopping its only a one movie type thing. As it is I'm hopping movie 12 has Hancock in it, she played a big part in the War arc and normally movies take place in a certian time. I think movie 11 takes place during series 11 before the group splits apart.
10 Movies is a lot, I think Dragon Ball Z beats it though that series has um I think 13 movies. I do think One Piece will catch up though in the end.
Ask for movie 8, well I didn't like it cuz it was a remake of a saga I already knew and love so I figured why bother?