Tempe '77. I kid I kid!
But seriously: My favourites are 21/23 77, Earls Court 24th and 25th, Snow Jobs (Vancouver '75), Houston '77, Bonzo's Birthday Party, Montreux '70, Fillmore soundboard from '69, Knebworth 4-8-79, Vienna '73, Landover 30-5-77, New York 11-6-77 and Conspiracy theory.
I'm a big fan of the '77 tour.
Edit: And in regards to Moon being onstage with them on the 23/6/77: I think it is awesome seeing Moon banging away on the tympani with Bonham on rock and roll. In the video you can see Jimmy look at Keith and Bonzo playing together several times with a massive grin on his face.