The LA is a bushed bearing engine while the AX is a ball bearing engine. The AX (and similar clones) have about double the power of an LA.

Horizon hobby, Hobby Lobby and several others offer reasonable priced 46 ball bearing engines for only a little more than the LA. Thunder Tiger Pro and Evolution engines are very user friendly and less than the AX in price, but just as good in quality and power.

Tower 46 engines have their own well documented problems with air leaks and othe things also. Until you have some experience, I would avoid the Tower engines. Outside of the fact that Tower engines are made by GMS, I have no experience with GMS so I can not comment one way or the other.