I bought a Split-Fire model SS244 3pt. splitter with 4-way wedge.  This machine will out-split anything I have used by at least double (volume). Myself and 2 helpers can split 10 face cords per hour, and this is small fireplace sized  material when finished.  It is a two-way design, which eliminates "cycle time" arguments, since it is constantly splitting, if you can keep it fed with wood.   If you are looking for a quality machine with performance, try one.  Also, keep in mind that with a 3 pt splitter, you can adjust working  height, and lay it on the ground to roll large blocks on it... this is much easier than trying to itch a big block up under a vertical model.  Split-Fire does offer a hydraulic log-lifter as an option.  I have tried every variation of splitter and believe that the 3pt, two-way, tractor-powered version is the way to go.  The 4-way wedge is nice, too ( it saves 2 strokes).