Def Leppard is definitely more popular than Judas Priest, because they reached a larger group of music fans than Priest ever did.
Judas Priest
Judas Priest
Judas Priest
Metallica is more popular than Judas Priest.
Scorpions were more popular back in the day, but maybe Judas Priest is more popular these days.
The Rolling Stones are definitely more popular than Judas Priest.
To an older generation, Judas Priest. To a younger generation, Linkin Park. However, Linkin Park eventually became more popular than Judas Priest by being more commercial.
Both very popular, but ACDC were much more popular for a longer period of time. So ACDC is more popular than Judas Priest.
Kiss
Nirvana
N Sync
Iron Maiden