I agree totally with the comments on the X-27, but speed and accuracy are important to getting the most out of it.
I used to split all the wood to heat my house by hand (did not get a hydro splitter till 6 years ago).
When I started, I used a traditional 8 lb wood handle maul, till one day the handle broke and the maul head bounced back at me head. Luckily, I used to box, and I slipped it, but it brushed my cheek going by. That was the last time I used one.
For years after that, I used a metal handle monster maul. Worked well, but I was young and strong.
I used someone else's X-27 once, and I went out and got one and have been using them ever since. In fact, I have 3 of them (got the last one for only $20 from someone who did not like it). I keep one up at the cabin, one at my house, and one in my truck.
I will split anything I used to split with a maul with the X-27, and it is so much lighter that I can go much longer even as I get older. I have also never broken one of their handles, so they are very tough. I never bring the hydro splitter up to the cabin, all the wood up there get split with the X-27. The Ash and Black Cherry are usually no problem, but the Sugar Maple and Black Birch can be tough if you don't wait till it dries out some and gets cold. Bad knots sometimes get noodled.