Zoglin didn't pick John Daly or Bud Collyer because he felt Daly was too stuffy and Collyer not much fun. But Collyer did show his versatility by successfully hosting both the frenetic "Beat The Clock" and the more subdued "To Tell The Truth."
Tom Kennedy did have two long-running hits before "Password Plus": "You Don't Say!" (NBC, 1963-69; ABC, briefly in 1975), and I suppose its similarity to "Password" made him a natural to replace Allen Ludden on "Password Plus"; also, Kennedy hosted the '70s version of "Name That Tune" in syndication from 1974-81, as well as a short-lived daytime version in 1977.
Wink Martindale had a long run as host of "Gambit" (CBS, 1972-76; as "Las Vegas Gambit" on NBC, 1980-81) and "Tic Tac Dough" (1978-85) and was one of the hottest hosts of the '70s and '80s.
How could they leave out Chuck Woolery, first host of "Wheel Of Fortune" (1975-81), and later, "Scrabble" (1984-89 and again in 1993) and "Love Connection" (1983-95)?
As for Groucho, I can actually see him losing interest in "You Bet Your Life" from the last two years of "Best Of Groucho" reruns; his retorts just aren't as sharp as they were in earlier years. The reason for the writers' giving him prepared jokes and interview questions goes back to the beginning of the show on radio in 1947: the early shows were live, and Groucho seemed hesitant at times as to what to ask or whether he should say what he was thinking, since he might get run off the air. A combination of audiotape and (on television) film solved that problem; Groucho was more relaxed, knowing that anything risque or just simply unfunny need never be aired. But he liked to say in private that he was known for his lightning wit, and it didn't look good for him to sit up there for 20 or 30 seconds trying to think of something to say--or to say what he was thinking--and those were the times he was most likely to depend on prepared material. Some of the people who worked on the show said he was rarely off-color, however; Groucho did come out of vaudeville, where even mild profanity was forbidden, and that's something that stayed with him at least when he was on-stage. But whether or not "You Bet Your Life" was ad-libbed or even partially scripted, no one could deliver the lines as well as he did. And as for the quiz, it was completely honest (although there were some accusations that William Peter Blatty was given particularly easy questions, given that he once worked as a page at NBC, "YBYL"'s network).
Roy Kammerman, head writer on "Who Do You Trust?", often said that Johnny Carson did everything off the cue cards (that would make sense, given that the show was a live half-hour with three pairs of contestants to be interviewed and quizzed, an end game, whatever interaction Carson had with Ed McMahon, and the all-important commercials), but Kammerman said there were times when Johnny could come up with something even better than Kammerman had written for him.
I'd also vote for the first successful game show host on television, Dennis James, who started with a show on DuMont called "Cash And Carry" in 1946 (still the prehistoric era, which I would argue ended in 1948) and hosted shows at least through the syndicated "Price Is Right" in the '70s. I personally eliminated Bert Parks, although he hosted two of radio and early television's hottest games, "Break The Bank" and "Stop The Music," simply because of his unparalleled ability to grate on viewers and because he was more closely associated with the Miss America pageant.