Generally speaking the manufacters recomendations are good. Also the purpose of the plane is most important. A trainer is totally different than any other in appearance as well as performance. Also so in all other aspects, function designates design. Yes there are some that must have all the power possible not usually beneficial but just there hang up. Definitly under powered is bad but overpowqered is not necassarily good. It will be heavier, costl more burn more fuel, may fly faster but not better. As with most things find the happy medium. One other note that is usually true bigger is better in regard to flight chararistics in respect to size of aircraft.