The most important thing is don't go below your cars recomendation and use the same brand and rating all the time.

I personally use 93 not because it gives me more power but because it burns cleaner, often people just talk about how a car doesnt need higher octane fuel becaue if your car was designed to run on 87 there is no chance of premature combustion if u stick with 87 so why go higher, this is true, but premium fuels also have a better composition and thus can burn cleaner and contain more energy