Hey partner, I'm no expert, infact I just bought my first used splitter and got it running, but I can offer you a little insight, and there are tons of other threads here with valuable info. This is gonna be a condensed version of a bunch of threads I've read.
#1. I have used several splitters, and they all worked well. I preferre to have the control valve handle, on the opposite side(across) from the engine.
#2. I thought I wanted one that was low to the ground to help ease the lifting process, but I hear that is worse on the back, as is working vertically.
#3 No matter what brand you buy, it is gonna work pretty well, so look for the creature comforts I mentioned, and trol the treads for more info, know what you
want, and then get it.
#4 Get it in Delaware, and save on taxxes! If you can't do that, then make sure to get a 10% coupon no matter where you go. Pretty much all the big stores have them, and some places give discounts if you sign up for their credit card.
#5 If you want a used one, prepare to look for a while. I found one via a radio swap meet,with a blown engine and fixxed it. I see them on Ebay, but most are far away, and over priced.
Good luck partnr.