I took Mark's comment to mean 'popularity wise', not 'talent wise' ...

I enjoy watching/listening to Michael Buble ... is he the greatest singer ever? ... maybe not, but then I don't know who is ... but I think the guy can swing a tune, sing a nice ballad, and mostly, have people enjoy his performance ... what I DO know is that many of us here would give our right (or left) testacle to do what he is doing ...
and let us not underestimate the musical talent and capabilities of some of these entertainers ... it was around the late 60's when I was at the Steel Pier in Atlantic city NJ ... I heard some music and walked into the big 'concert' hall where a big band was rehearsing ... a short time later Frank Sinatra JUNIOR came on stage and starting rehearsing with the band ... after a while the music director comes in with charts for the entire band and says to Jr "this song is on the top of the charts' we should include it in the show -the song was "Up, Up and Away" by the 5th Dimension ... he hands out the charts and the guys start 'fiddling' around with the tune while Jr is going over the lyrics ... a few minutes later the conductor has the band run through it - like they were playing it for years - as Jr was listening and looking at the score ... when they finished, Jr says "saxophones, 4 bars after letter such and such you are playing a B - make it a Bb ... that changed my impression that Jr was only making it on his father's coat tails ...