Three totally under appreciated bands: Vain from the Bay Area, Heavy Pettin from Scotland, and Q5, who included Floyd Rose.
Vain to me is one of the greatest bands ever; they are kind of like Guns 'N Roses, if everything they did was as good as Appetite for Destruction. Their lead player, Dylana Nova Scott (formerly James Scott), is the biggest badass, and is the founder of the 3rd Power Amp company, who also makes unusual guitar pickups that use different magnets for bass and treble strings. Her playing kind of reminds me of a cross between Slash and George Lynch, in the best possible way. Davy Vain to me just has the most rockin' feel consistently in his songwriting. The ones to start with are No Respect (produced by Paul Northfield, the sonic force behind Moving Pictures), and All Those Strangers. Epicly Huge Feel, and truly in the top tier of greatest rock bands ever, in my humble opinion.
For Heavy Pettin, they were always compared to Def Leppard, but I don't agree at all. Their first album, Lettin' Loose, was the first thing Brian May produced, and it sounds awful, but it has such unbelievable energy and feel. Try Love On The Run; it's just the greatest thing ever. Off their second album there are several epic tracks, like Northwinds and Soul Survivor.
Lastly for Q5, the two albums with Floyd Rose are great. Really, I love everything they did, even when they changed their name to Nightshade. The second album, When The Mirror Cracks, is completely epic sounding; it truly could be the alternate soundtrack to the movie Bloodsport, and that's one of the highest compliments I could give.