The comparison between the UK and US systems fails in this respect, mainly because we do vote for our PM, who is chosen by members of his party alone. We have the rough equivalent of your state elections, where we choose a candidate to represent us in Westminister, and in some cases that's the last we hear of them till the next election. This is not always a bad thing!
So all that most of us get in this country, is the choice of 4 or 5 mediocre, self serving wannabees. The late John Smith has been mentioned as someone worth voting for, but I think that part of his legend is best served by the fact that he is dead. I admire conviction politicians like Tony Benn, Enoch Powell,and Maggie Thatcher, not because I share their views, but because the stuck to their beliefs, and didn't trim their sails to court popularity.
Who would I vote for in the UK today? The only politician I admire at the moment is Margaret Beckett.
Giok