RE: which engine?
I have experience with all 3 of the motors you listed.
So my choice would be...number 4. The Thunder Tiger 46 Pro.
Its clearly one of the best values in a 46 size motor out there.
I have 3 of them and wouldnt even consider anything else
in that size.
If you simply must have one of the others and dont
mind paying the premuim price then go for the 46AX.
It will be the most trouble free. But seriously...the TT46
is every bit as good as the OS for a lot less money.
Mike Hammer