Which one of these would be the best engine?
I'm putting it on a Great Planes Super Sportster 40.

Between the two, I'd probibly go with the TT.

Easy. Thunder Tiger. Best $75 engine out there.

The TT .46 Pro is more user friendly, is built to a higher quality standard & is fundamentally more powerfull. The Tower Hobbies .46 & the GMS .47 are the same motor (despite the "47") & both will slightly out power the TT with the as-supplied mufflers, however, if you put the GMS/Tower muffler on the TT .46 Pro, it will blow the other two away.

Go with tthe TT.

Definitely, go for the TT .46 Pro, powerful and reliable.

I got the TT PRO .46 and I love it. Get it over the tower anyday

I guess the TT's have it. That would be my suggestion as well.

Mark Shuman

TT Pro 46.

I've had 'em both. My TH was powerful, but I started getting deadsticks like crazy. Would run great on the ground but die once in the air. No one could figure it out. When I deadsticked into a pond I ripped out the TH, sold it for $5 (because the guy wouldn't take it for free) and went with the TT. It has been the best running engine I've ever had. Smooth and reliable. And with the muffler from the TH it's one powerful engine.

This is too close to call
I had a Tower 46 and it was a giant headache.