My favourite at the moment for "How Many More Times" is Tampa 1970-04-09 (I've always enjoyed the feel of this gig, though I hear the medley from memphis 1970-04-17 is much better, just much worse sound quality), but a personal favourite of mine for "Whole Lotta Love" is 1971-09-29 (The power of the guitar tone on "Fortune Teller" combined with Bonham's 'samurai' drums could power a small city and the Jamming on "Good Times Bad Times" and "You Shook Me" is out of this world).
Whenever people ask me which medley is best to listen to first, I always recommend the Whole Lotta Love from "Blueberry Hill", because I feel it doesn't go on for too long and captures a good amount of tunes that show off Zeppelin's chemistry nicely (Plus that combination of "Honey Bee">"Lemon Song" is my personal favourite Robert Plant Moment").