Ringed every time given the choice. If you baby an ABC (air filter, carry it out to the flight line and so on) it MIGHT last as long as a ringed engine before needing an overhaul that costs nearly as much as a new engine. Personally I don't think there's any difference in power at all between 2 otherwise identical engines.

I can put up with the different and longer running in time so I can have an engine that'll last just about forever