Football, men's tournament...chapeau to superiority in 2004, but to me the tournaments after WWII don't have the same value than those before, which were the only ones played by the truly best teams and players available.
therefore, I pick Italy 1936, 'cause I'm heavily biased (especially during those WC days) and 'cause that was really a great team (World Champions in 1934 and 1938, too), as a more serious vote should go to Uruguay 1924 & 1928, when they were a real football machine...unstoppable.
Volleyball, men's tournament...what the hell? the greatest team ever ( Italy in the Nineties) has never won an Olympic Gold medal...why should I vote for some teams that weren't as good? OK, that's a game, so I pick the team that won most of the medals we should have gotten, Brazil 1992, 2004 and 2016.
and tbh, those teams were great as well, not that they didn't deserve all of their success...
Volleyball, women's tournament...this is a no brainer, Cuba 1992, 1996, 2000 was something special, most likely the highest point ever reached by the sport of Volleyball in the women's division.
Fencing, women's Team Foil...once again, Italy 1992, 1996, 2000 (and morally, 2004...if only it wasn't for the most cruel, stupid, criminal rule ever applied to the Olympic sports, the weapons' rotation in the team events ) are and will always be unmatched in this discipline.
Fencing, men's Team Sabre...this one, instead, is a very difficult choice, as we have quite a few really great dinasties that surely deserve at least a mention of Honor. was amazing in the early part of last Century, Podzniakov's Russia in the Nineties was remarkable (and almost unbeatable), but honestly, I think that the current generation of South Korea 2012, 2020 (and morally, 2016, if not for the same rule that heavily penalized Italy in the women's Foil) truly represent the best team ever in modern Sabre, which is to be considered more competitive that the heroic age's, at least because of the way bigger competition there's now compared to may years ago.