The only song that I know from Elton John is "Benny and the Jets". I like the song, but I can't really say it's my favorite song by him since it's the only one I know from him :P.
I'm not a fan to be honest but I do love pinball wizard from Tommy. Yes it is exatly one of his songs but it is brilliant and his shoes in the movie are great.
I don't know if he has had one bad song. The song Rocket Man was also brilliant. And as snazzy mentioned Tiny Dancer, Philadelphia Freedom and Tiny Dancer are also really good.
But his cover of Pinball Wizard was a travesty, plain and simple.
I'm not sure how much influence he had on his role though or if he was just cast and told to sing it.Thr Who's own version is amazing especially live but it fits in ok with the movie which isn;t that good (I love it but its a bit iffy)