I have the impression that you are fairly new to flying. As CGRetired said, the hp is a fable. In my opinion, you should be looking for a reliable, easy to operate, relatively trouble free engine.

Some of the most "User Friendly" engines I have encountered have been (in no particular order): OS 46 FX/AX, Thunder Tiger Pro 46 and Evolution 46NT. 99% of these engines will run reasonably well right out of the box, require little (or no) breakin and are fairly easy to fine tune.

While ringed engines will last longer than an ABC/ABN engine, they require a substantially longer breakin period and in many cases are not only heavier, but will not achieve the same rpms as an ABC/ABN engine.

The big advantage to a remote needle valve is that it keeps your fingers away from the prop. The big disadvantage is that many of them are made as part of the backplate of the engine. In the event of a crash that may damage the needle valve, the backplate needs to be replaced.

As for the Tower (made by GMS) engines, while they are a little more powerful than other makes (due to the muffler ), they tend to be plagued with air leaks and poor transition problems. If you get a good one it is fantastic, if not, you will be pulling your hair out trying to correct the problems. I have had 3 Tower 46 engines and every one was a dud. I spent more time TRYING to find all the air leaks than I did flying.

Hope this is of some help.