David Gilmour easily. If you've heard the Live 8 performance, you'll know Roger Waters voice is all croaky and strained, even on the speaking parts of "Comfortably Numb", whereas David's voice seems to be holding up well. Anyone can play the bass as good or if not better than Waters, but try finding someone to play guitar as good as Gilmour.
When "The Wall" came out, I couldn't listen to it, too political for me. It still is, but I managed to make a single CD out of the double CD that I call "The Short Wall". The courtroom track is just crap.
Lee.
His voice must have gotten better than, as he sounded better than ever during the Dark Side and Wall tours in the past 3 years. I'd read that he'd gone through a lot of vocal training to prepare for those tours.
Gilmour still sounds good as well, and if anything his guitar playing is even better or at least more effortless (always a trademark of his).