Here's a conservative list of LW that could beat Fisher not counting the champ. Several on this list would dominate him.
Rich Clementi, Nate Diaz, Sherk, Maynard, Edgar, Griffin, Wiman, Tavares, Franca, Florian, Huerta, Joe Stephensen, Manny Gamburiyan, Guida, Danzig
Pretty sure Wiman got KTFO by a flying knee from Fisher. Spencer isn't my favorite fighter, but he has some impressive wins and could hang with most of the guys on that list.
Favorite Fighters by Weight Class:
MW Rich Franklin
HW Still supporting "The Crocop"
LW Frankie Edgar
WW GSP (I'm a closet Hughes fan)
LHW Whoever's fighting Tito Ortiz
All-time Genki Sudo