With a Northern Tool store nearby, I think that your decision on where to buy will be a simple one.
I upgraded to a splitter this year, after a couple years of splitting by hand. In the past year I was getting too many gnarly, knotty pieces of hickory, maple, and whatnot, that splitting by hand was tedious and stopped being fun. I wanted to find a splitter that was light and small enough to fit in my small garage and to single-handedly load into my trailer. And I wanted a horizontal-only unit.
In the end I went with a Timberwolf TW-P1, with a 4-way wedge. If y'all knew what I paid, you'd probably have a heart attack and some serious jealousy; suffice it to say, I got an incredible deal. I would have had a harder time justifying an entry-level Timberwolf at $1800-2000, and would have given serious consideration to the merits of either going with one of their larger/faster models, or going with a Northern Tool or Speeco/TSC machine.
I think that the decision to go horizontal or horizontal-vertical will depend in large measure on three factors: what you're splitting (species, size), whether you work alone, and whether you intend to break huge chunks apart with your saw first. I split whatever I get, from 8" cherry and ash up to 70" oak. I have the ability to rip blocks into manageable chunks and often split with friends, so most everything can be broken down to pieces liftable by one or two people. For me, the horizontal choice was the best one.
Another consideration with the horizontal models is the ability to run a 4-way wedge. I am SO pleased with the 4-way that I have on my splitter, especially for smaller logs. I split most of my wood smaller than most of y'all, since I burn in fireplaces and firepits, and split for family and friends who do the same. The ability to split a 12" log into quarters in one pass is a great thing for my splitting activities; it would take two or three passes with a regular wedge setup. The scale of efficiency that comes from the ability to run a 4-way more than makes up for the lifting of the logs, in my opinion.
Yet another point to consider is the quantity of wood you'll be splitting per session, and what you plan to do with it as it falls off the splitter. The horizontal-only splitter piles the wood beyond the splitter operator's work area, and when the pile gets too big the logs being split either push the top of the pile away to make more room, or they push the splitter away from the pile. Either way, it is possible to split all day without having to dig out of a pile of split wood, or to have logs falling on or popping in the direction of the operator. Again, you may or may not see this as a virtue, but it is worth mentioning anyway.
Lastly, tonnage: 20 tons will split darned-near anything you care to split, and this is usually what a 4" cylinder is marketed as being capable of producing (calculated at 3000psi, which few splitters operate at anyway). Paired with a 11gpm or 16gpm pump, you'll have 13 or 9second cycle times, respectively. A larger cylinder will require a substantially larger pump (22, 28gpm) and larger engine (11hp, 15hp+) to produce workable cycle times. The idea of a 20second cycle time seems crazy to me, but that is what some of these massive tonnage budget splitters are going to give you.
Anyway, I just wanted to share a couple thoughts on the virtues of the horizontal-only splitter, since it seems to be an underappreciated tool in this thread!!