If you're a true lover of comedy, you have to back Fawlty Towers. A series that has a legacy based on only twelve episodes! How many sitcoms in this tournie have that many or even less than that?! This is one of the pure pieces of gold that you are able to treasure because it wasn't too much or too little, it was just right.
Not to mention you have the stellar cast that is led by John Cleese, while Monty Python brought him to the dance, this showed he can be a standalone comedian with his own series and he brought his A*** Game, yes I gave him three stars because that's what his performances were in Fawlty. I can't say much about Laverne & Shirley, think I only seen a couple of episodes, but given I can't remember much about them, it pretty much says how Fawlty Towers stands out as a series.
If you truly appreciate pure comedy gold, then vote for Fawlty Towers, without a series like this you would not have inspiration for generations that follow.