Welcome!

This is a hobby that a lot of people end up doing for several years. With any thing there are expendable pieces and investment pieces that comprise the whole package. With this hobby, engines are an investment piece and the planes are an expendable piece. If you spend the money to get a quality engine you will likely have it serve you in several different airplanes as it seems, and most would agree, that the engines outlast the airplanes.

So to your question now with my perspective out there... I would recomend an O.S. or a Saito in the recomended size range up to 1.00, if you choose to go with a four stroke nitro. If it was my plane, It would get a DLE 20cc gasoline engine.