Tyler, I have been using a splitter that runs off my tractor hydraulics. It isn't the fastest in the world, being that my tractor is a beat up 1963 Super Dexta, but it seems to be at least as fast as a lot of the gas engine ones out there. It has the advantage of being less expensive (assuming you already have or are going to need a tractor with a Category One 3 pt hitch) than one with its own engine, and it is one less engine to maintain as well.
It has another advantage in that it goes from horizontal to vertical in a few seconds for those really big logs you will be splitting and can't lift to the bed.
Good luck with it!
professional woodturner, instructor, purveyor of woodturning videos