That's kind of like asking whether Northern tissue is the best or if "the other brands" are just as good. It depends whether you are comparing it to Charmin or whether you are comparing it to the 1-ply store brand.
The difficulty with most of the non-Clover Wonder Clips is that they don't have a brand attached, so you get what you get. Sometimes you'll get lucky & they're every bit as good (or close to it). More often, it seems the non-Clover ones have some sort of issue whether it's the spring, the type of metal rusting, burrs in the plastic or whatnot. Here's a link to a website where the blogger asked followers to share their experiences:
http://so-sew-easy.com/budget-or-quality-wonder-clips/