Without a doubt Heartland and Amaze Me in the AOR sphere. In progressive metal FATES WARNING deserve a much bigger audience for their clinical but emotionally rendered metal. SAVATAGE is another band that springs to mind.
Pure hard rock, THUNDER were fantastic, excellent live performers. TEN also deserve wider exposure.
In the power metal sphere STRATOVARIUS and EDGUY for awesome melodic metal and HELLOWEEN alsso deserve greater credit for inspiring so many bands.
In the singer songwriter stakes I would put TOM PETTY and ELVIS COSTELLO, the latter deserves a much bigger audience.
WARRANT are in my opinion much better than the press allows. There is a definite reassesment of the merits of many 80s bands going on now that is partly based on the overall mediocrity of much of 90s music.
Oh and finally I nearly forgot, an excellent hard rock band called DIVING FOR PEARLS that released a brilliant album that flopped. And NIGHT RANGER should be much bigger than they are...KAOS..