I have Northern's 37 ton log splitter and has a Honda motor(I thinks about 10 hp). It starts very easy and will split anything and has quality parts on it.
BUT; it is big and heavy and hard to move around by hand. Also it is too balanced on the axle, meaning no tongue weight. So, when you are pushing it by hand and you hit a small twig or hole with a tire, the tongue wants to come up and hit you in the chin. Also, you have to use the drop leg to keep it from tipping when you split horizontally.
A friend has a Yard Machine 20 ton splitter that is much lighter and does almost everything my Northern splitter does. It is much easier to manhandle around the yard too. And about half the price.
That being said. Make sure you buy one with some type of log extractor on the cylinder so it will push off a stuck log when it retracts.
DO NOT buy a log splitter from Harbor Freight Tools! you will regret it. been there.
$.02 from Russ.