Call Ken at Prop Gods. www.propgods.com They can give you the best advice. It helps to know your numbers first. I switched to 4-blade props and it was a game changer.
Depends on what you currently have and what your current data: max rated RPM for whatever motor you have... max RPM at WOT throttle when running... current prop specs. What are the answers to those ?
However, your best bet is going to be to use the standard prop for your engine and add something as simple as Smart Tabs.
What motor? Here's some fuel economy numbers for a 192 Freedom, which is the same as the 192 Tournament, and that has a Yamaha F200 on it. They used "a 14.25" x 17" three-bladed stainless-steel prop."