Better late than never
!
I used to be Huge (160x160 in Conquests, although 180x180 in Vanilla) all the way person. I'd occasionally push it, I remember having a 220x220 map once. But the amount of time I want to spend per game tends to be a bit lower these days, and I've played enough GOTMs to find enjoyment on Standard (100x100) size maps.
So my sweet spot these days is probably somewhere around Large (130x130 C3C, to 140x140 Vanilla). Maybe a bit larger with rules that prohibit desert/tundra settling, then Huge is still okay. Beyond that though, I find the overhead, both of managing my own empire and the AI's turn times, doesn't generally outweigh the increased epicness of a larger map.
In other news, I've concluded that the world is simply too big for me to play a whole-world map
and have the level of detail I'd like to have in, say, France. I've been spoiled by more focused maps of France with lots of detail (in Civ3 but also in other games), so a map of France on a world scale that can fit three cities seems too small, but a map of the whole world at sizes that would make me happy with France is too big to be playable. So the happy medium is a map of, say, Europe, that has detail and is playable.