I don't think this thread is going anywhere anyway All of my eBay earnings come from stores very similar to BANS, but I write my own scripts to pull in the eBay RSS - the end result is basically the same as a BANS store. Except most of my stores look cheap and crappy.
There's no right or wrong answer to this question. If there was a best company, or best companies, we wouldn't tell you (because we'd be using them already). Find a marketing method first (PPC, ads on a content site, etc...) and then choose a merchant that PPC or your content site would work best for.
I tried PPC - maybe I didn't have the patience, or maybe I didn't know what I was doing - but it was a waste of time for me. I use good old fashioned SEO
There are several large earners, but ebay is by far one of the largest. Anyone can make darn good money with the ebay program.