I will have to drag my sword and mace to this battlefield because I have all Riot albums since "Thundersteel" (plus a "Rock City" and "Fire Down Under"), so I guess I can talk about one of the most respected American metal bands, and true pioneers of the prower metal movement.
When Mark Reale established the post quartet Riot with Mike Dimeo (vocals), Mike Flyntz (guitar), Pete Perez (bass) and Bobby Jarzombek (from the "Thundersteel" and on days), the band became one of the best melodic power bands around. All albums are really good being the higher points (IMO) "Nightbreaker", "Sons Of Society" and the lowest (but not bad) the last one "Through The Storm" (now Bobby Rondinelli on drums). "Inishmore", "The Brethen Of The Long House" and "Shine On" (live) all have great moments and not so great (let's call them "fillers"). The band had cover other people's music since "Nightbreaker", but all of them 'Burn', 'Whiter Shade Of Pale', 'Out In The Fields', 'Only You Can Rock Me' and the instrumental version of 'Here Comes The Sun' (tribute to George Harrison) are all played with respect, passion and quality.
When it comes to Riot I'll defend them a lot, so far they hadn't sell out, screw up or going lame. Maybe is not "Thundersteel" time anymore, but they retain all the quality they have showed since 1977.