Let's do some sitcom crossovers.
Fresh Prince in Bel-Air and Family Matters. While it would be iconic to see Will and Steve meet up, I think that we're all really here for the interactions between Uncle Phil and Carl Winslow.
Curb Your Enthusiasm and It's Always Sunny in Philadelphia. Larry and his friends interacting with the Gang would lead to clash of social classes and an absolute collapse of social niceities between them. And it would be hilarious to watch.
Keeping Up Appearances and Fawlty Towers. Hyacinth Bucket meeting Basil Fawlty. The jokes would practically write themselves.
Parks and Recreation and Brooklyn Nine-Nine. These are two of my comfort shows and I think it would be fun to see them crossover.