I first viewed YSOS as reruns during my childhood. Later anthologies and "best-of" films and specials kept the top quality moments accessible. Was the actual show close to uniformly good? No. Yet the high points were so lofty it demands recognition for what it could deliver when at its best. Plus being live, there were some occasionally unintended jokes and flubs adding to the unexpected nature of the proceedings
The four main comic performers in the shows heyday (Sid Caesar, Imogene Coca, Carl Reiner and Howard Morris) wrested more laughter out of me from the selected samples(culled from a series run of four years) than most other shows could in a decade. Also, it is important to point out, the level of my reactions; more belly laughs than I could count. The common (but not exclusive) main personalities of these four meshed and conflicted excellently: Sid - usually a buffoon aspiring to prove his skill or masculinity. Imogene - an every-woman, often with a self-professed ability to be an irresistible femme fatale; I know beauty is in the eye of the beholder but... Carl - often was a reactionary twerp or easily flabbergasted straight-man. Howard - the ultimate lackey, hanger-on, unwanted relative and/or general pest.
Their depth of routine choices was phenomenal. Most often cited is the skit where the four of them portray automatons on a clock in a mediaeval Bavarian town. Each one performs a piece in a routine mechanically programmed to play with the striking on the hour. The skit shows the systematic eventual chaos (an oft-used YSOS theme) developing with each ensuing hour. I won't get specific because I believe dropping a spoiler on a joke is one of the greatest social sins. Needless to say all goes wrong.
There are so many other examples... Off the top of my head:
The team's take off on From Here to Eternity (Obscurity with them if I recall correctly).
Their rendition of This Is Your Life. Morris' Uncle Goofy is the final straw breaking my resolve not to fall into total laughing, practically choking hysteria
A skit depicting a crew inside a U-Boat. (I love how Caesar would weave Yiddish and plain gibberish into the routines if a foreign language was called for - hence a twisted inside joke of militant Germans speaking broken Yiddish).
Add in spoofs of early Rock'n'Roll groups, marital spats, the "Man on the Street" interviews by Reiner (of Caesar), etc. etc. etc. They attained peak quality too often to be dismissed as out-dated (heck they're often regarded as trendsetters), irrelevant or totally unsatisfying. Though I strongly believe each of these four could deliver the top performance in any given routine (they consistently were funny), I must convey a personal opinion. In my estimation Imogene Coca has never been surpassed as a television comedian of either gender. In my mind, her closest female competition is another early TV star, Audrey Meadows of The Honeymooners. It's a tough comparison, though, as their roles were exact opposites - Coca, a possibly limitless amount of comic atler egos - Meadows, portraying one character so fully she could breath humor into any situation.
One interesting tidbit: Coca and Morris appeared in more episodes than Caesar.