I'm sorry but people like Dickinson, Gillan, Dio, and Tate are NOT melodic rock vocalists - they are metal or hard rock singers (although they've all proven their softer side at one time or another...). So I'm sticking with:

Glenn Hughes
David Coverdale
Paul Rodgers
Brad Delp (Boston)
Ray Gillen ('Dream Runner' counts as melodic rock, right?)
Freddie Mercury
Joey Tempest
Fergie Fredericksen
Jimi Jamison
Lou Gramm