I will say the Thunder Tiger Pro .46 is the best option in my opinion. You will very rarely hear an ill word spoken of the TT Pro .46. It is such a nice little engine to live with. I have had a few over the years and they last forever and are very easy to tune. The TT GP 42 is also another good option. I have had one of those as well and they are a great bargain. THe only downside to TT motors is parts availability. I have had great luck with
www.thundetiger4u.com though.