I think Sophie Ellis-Bextor would be good with another Freemasons track, or something produced by Cahill or Wideboys. In fact I've told her as much on Twitter. See how she responds to that!
I've also said the same to Luciana (as in Bodyrox featuring, and Tiesto and Wolfgang Gartner Featuring, etc)
Who would you want to represent the UK?
I think Loreen has proved that if you just enter a singer with a great dance track, and promote it around Europe (She must have surely? She was in all the Euro charts before Eurovision) then you can do great out of it!