I never get chance to watch during the day, so the ITV4 show is perfect for me. Phil L and Paul Sherwen balance each other's commentary well and aren't afraid of contradiction or disagreement. Imlach's research and ability to summarise is really professional. Boardman's occasional input is interesting too. And the guy (I forget his name - sorry!) who does the magazine-like background pieces adds another dimension. It's a well constructed programme with something for the casual viewer and the enthusiast.
Ok - the adverts are a pain, and I have a real thing about the frequency, mind-numbing style and duration of adverts in general nowadays. It wouldn't be as bad if the same ad's weren't repeated so frequently.
On the whole though, I think TdF on ITV4 is the best cycling coverage I get to see in the whole year.