No such things as "best". You have to talk about what you want the boat to do for you. You also need to mention what your current performance is with your existing props (and what they are) and what your engine's MAX RPM range is. For example, what's the max WOT RPM and speed you can obtain? Don't be gentle - this is an all out sprint that you have to do - really max it out with full throttle and keep trimming up until there's no increase in speed. For best results, do this with your normal load in the boat.
