Definitely those three would be the biggest. I had only vaguely heard of Chrissie until I moved to Adelaide and heard her radio show and I know she was nominated for and won Logies but I had never seen the shows. There are a lot of Logie winners I have never heard of. I think it depends on the audience. I am much more familiar with Fitzy because of Before the Game, the Project and his radio show, so I guess in my world he seems the most prominent. For some Blair might be considered most successful. Definitely in the UK.
I know Tim Brunero has been consistently involved in radio and ABC stuff since BB, but not to the level of Fitzy/Chrissie. Pretty much successful journalist stuff rather than entertainment based.
Chrissy really is brilliant. She is one of those rare people that are interesting, funny, beautiful and although she is not afraid to have her say and be honest she manages to do so without offending the masses for the most part. I would watch and listen to hear any day of the week.
My other faves were original tim, 2012 ben, and 2013 tim (although he was the only one i hated in the beginning).
but since bb chrissy has really shined. Smart, funny woman!