There are so many left out I couldn't stop at 5. Here's my top tier:
1) Johnny Olson -- The greatest there ever was. The greatest there ever will be.
2) Jay Stewart -- LMaD takes a certain type of announcer. Jay set the standard there and was awesome in the 80s as well.
3) Rod Roddy -- He replaced the legend at the top of this list and held his own. He got it after a good run on PYL.
4) Gene Wood -- That voice stays with us after all the great work he did for Goodson-Todman.
5) Johnny Gilbert -- Few realize he was actually a host in the early 60s. He's made an even better career behind the mic.
6) Charlie O'Donnell -- Such a fluid voice; very easy to listen to. Also has personality, which is required to make this list. Even with over 30 years of continuous service, gets overshadowed a bit by those above him.
7) Don Pardo -- Probably would be higher on this list had he not stayed in NYC after most game show production switched coasts. Still does a great job on SNL.