Well, he was a superstar, but my all time favorite was Roddy Piper in the 80's. While he doesn't fit the description of a non-superstar, that was a time and place where next to nobody rooted for heels. There were probably some "smarts" who quietly did, and I know in the NWA Flair was incredibly popular as a heel. But in the comic book WWE days, that was pretty much unheard of in that territory.
I guess I always kind of gravitated toward natural heels who's heelishness was being an absolute a-hole, not on a ready made gimmick like being Russian or Iranian or being a dentist, LOL. I liked guys like Piper and Orndorff and Ken Patera and Bobby Heenan.
Big King Kong Bundy fan, really liked him. Liked The Missing Link. Mister Fuji. Jesse Ventura.
I can't think of too many babyfaces I really loved. Andre of course. Really liked Ivan Putski.
My favorite jobber was no doubt Iron Mike Sharpe. That guy was a great heel jobber. Never saw him win a match, but he played the heel great.