Faster, cheaper, better. Pick two.
Im surprized that rotaries only got a passing mention here.
This is what I have been looking at for my project, they seem perfect for aviation.
A NA 12a is good for about 120hp, and a 13b about 150. With mods good for much more.
The best thing about a rotor is that once running, they tend to keep going. Even with the failure of a rotor they still produce about 40% power.