Single stage if loading slugs or buckshot, progressive if you participate in the clay shooting games using birdshot. You can load single stage mode on most progressive presses, but it's usually not perfect, and not meant to be used that way primarily. Single stages are made from the get go, to get your hands in there, and make life easier when doing it all the time.
I've got two MEC single stage presses, because I shoot slugs and buckshot mostly, and I like em just fine, never tried hornady, but I'm sure they work just fine too. Don't get caught up in brand naming, and be another brand queen like way too many douchebags here who talk more trash than teenage girls about the brand they hate, and chatter on and on (also like teen girls) about the brand they love. Both Hornady and MEC have been around for decades and are tried and true products. Lee is fine too; and although some people have been known to load many thousands of shells on it, it's made more for low volume shotshell reloaders and as such has a very low price point.
I use alot of Lee for metallic reloading, but I prefer the MEC for shotshells, because I spend many, many hours on it, and I need to load 10 gauge which is something the Lee shotshell loaders don't do, but I was able to get a 10 gauge conversion kit for my MEC and can go back and forth.
Yes, the EE will list used ones fairly frequently if you've got more patience than money.