Another figure worth mentioning on this thread as a real pioneer for what's being discussed was probably Paul Rodgers. In his days with Free one of the most melodic hard rock bands to ever exist, they basically sounded like a ferocious dog that was permanently meshed up and kept on his lead, I always wished they would set that dog free but it never happened............all credit to them for their discipline
! Anyway when the band folded Paul Rodgers went onto even bigger acclaim with Bad Company a supergroup of Free and Mott the Hoople members (I'm sure you already know all this guff but mentioning for those that might not
) Now that band was probably one of the prime examples of what was an early incarnation of AOR or soft rock as I like to call it was, an AOR band at the heavier end of the spectrum, in fact Foreigner were probably their counterparts in the 1980s. They ticked all the right boxes for AOR, great vocalist, great musicians, ballads and big commercial appeal (with Peter Grant as manager that was no surprise) Point I'm making, is that this band would go onto be very influential on AOR and melodic metal, which as Almauro said is not really a sub-genre but a convenient grouping for metal at the softer end of the market.