I'd have to go with Jojo's Bizarre Adventure as my favourite show. I have a real fondness for any show where if you try to explain the plot, it sounds more like recounting a fever dream you had, and JJBA is the absolute best for that.
The best part: That's just the plot of part 1. The show gets exponentially weirder and more complicated as it goes on. I debated using the part 4 video as a good example, but the plot by part 4 is so complicated that going at the same pace, and glossing over the same amount of unnecessary information, it takes the same woman
16 minutes to recount it all.
In terms of shows with actual serious stuff to say though, that win me over with nuanced, complex character writing, i'd probably have to go with Bojack Horseman. It's a genuinely fascinating show that takes a real unflinching look at what it even means to be a good or bad person, how hard it can be to fairly evaluate ourselves, and how complex it can be to try to be good and make good choices, in spite of the damage that's been done to us throughout our lives. It's an incredibly philosophical show, presented through the lens of a goofy cartoon about a alcoholic talking horse.