I feel for you. Unlike you, my local shops are free to sell gear that is newer than 2 years old.
Hands down, USB 3 is faster than SATA.
When you say faster, if you mean slower, you'd be right.
Sata III = 6Gb/s
USB 3 = 5Gb/s
I'm not sure who's feeding you this information, you should do yourself a favor and stop trusting them. I hope it's not your local computer store.
Don't take everything on that list as literal speeds you'll get. Lists like these are good place to start learning maximum outputs to help working out potential bottle necks in networks and systems when designing workflows and how to increase performance for machines in post production.