Grip with a FH does take some trial and error to find what works best for you. One grip might produce more spin for you but also make it a little harder to throw on-plane. I think it's more of a balancing act between grips and throwing planes that really determines which grip is best for you. I utilize more of a control grip more than the power grip because that grip is more consistent for me. (I'm FH dominate with a controlled distance of 350', max 400'.) But, to answer your question directly, I think a power grip generates more spin than a control grip which generates more spin than a fan grip. Try them all as they all have their uses.
I also think that more focus needs to be put on the amount of wrist-travel (from open to closed) is a little more important than the grip. Most people that haven't really worked on their FH tend to throw their FH with mostly arm and little wrist-snap. This produces a lot of speed but not a whole lot of spin.
A good place to start is to work from a standstill. Try not to use a whole lot of arm movement and mostly use your forearm and wrist to generate spin on neutral, slower discs. This will ultimately get you where you want to be faster as it will help you maintain your throwing plane as well as help with wrist-roll problems that will inevitably pop up. Once you are comfortable with getting smooth, flat releases and flights, then you can start incorporating your upper body/upper arm to start generating more speed. At this point, you can also start working on weight shift. Once these things (upper body and weight shift) are working together, then you can start utilizing your lower body (run-up) to generate momentum. Working in this order will help with getting your timing right quicker than trying to do all of it at once. As with a BH, the same principals are the same with a FH. Power and distance comes from form instead of raw strength.
During casual rounds, you can work on most of these things by throwing your upshots FH. I personally feel that trying to throw off the tee FH for distance when you haven't developed your FH short game can hamper your FH development. I know it did for me and I had to re-learn how to throw FH.