It depends on what and how much you split on what size you would need electric or gas. I would look at DHT (Dirty Hand Tools). They look like a good one and are sold at Menards around here. Just had a big sale last week for their 27 ton $999.00 with a rebate. Has a Kohler horizontal engine.
I own a 22 ton Huskee (speeco) from Tractor Supply. They area around $999.00 and sometimes on sale cheaper. It does everything I need it to. No major complaints. Very good splitter and goes thru any wood I have put in it. Elm, oak, whatever. Only problems are it has a smaller fuel tank and the briggs engine doesn't have a choke. I keep in a warm garage so starting is fine for me, but in the cold it is harder to start. I didn't think the gas tank would be much of an issue, but if I am splitting for a day it seems like I am always refueling.
If I had to do it over again, I would look at the DHT as the engine is better and is on the correct side away from the operator.
The ones I looked at were the Speeco/Huskees, Northern Tool and a green made in China at Menards. Went with the Huskee mainly because of price. I like the option of vertical and horz. I do most horizontal, but some big pieces I start with vertical. Some guys here like to do all vertical. Depends on height, back and just what each of us like. Most of the spendy professional grade ones are horizontal only, some with log lifts. Another thing to look for is some horizontal only have fixed wedge and vertical option ones have moving wedge. All I have ever used is a moving wedge, so that is what I was looking for. The bigger ones also have slower cycle times and weigh more if you are moving it by hand. The slower cycle time is not a big deal if you are splitting tough stuff as the smaller ones are running the pumps in slow 2nd stage a lot.
I am not a big fan of the ones with the front-attach cylinder like the MTD's. I guess I would rather have one with a standard cylinder in case I would ever need to replace it and be able to find one off the shelf. Do some research here and on Hearth.com. Lots of good threads on splitters.