I think there are also a number of threads on this subject, to give you others thoughts on this over the years, in case you don't get enough responses for your taste.
I've taken Credit Cards since 1997.
I used USB and was unhappy with them, mainly because I leased to own the terminal... and that took a long time to pay off.
Since about 2001, I have been using Wells Fargo. It's attached to my business account and my business acct. fees are waived since I use them for CC services.
I do believe that it has increased my sales dramatically. Nowdays about 90% of my clients use this service.