I'm gonna have to agree with Suragaha on this one.
If I had the power of removing a map, I'd remove them all and remake them.
But, I shall answer the question, and honestly......
I think I'd remove South Pole.
Because it's literally a giant field of snowy hills.
Nothing else.
Bonfire has enough activity and things in it to keep it interesting, and Cape really can't be removed to me, since, well, it has portals to custom maps and whatnot.
Ficho Tunnel.... I wouldn't remove that one. Same reason as Bonfire.
Fluorite is the largest of the maps, and has a lot more roaming spaces, things to look at and see, and activity.
Temple of Drams.... It doesn't seem to be that frequented, so I think someone could get away with removing it, although it is pretty.
AI and Sky's Rim I'd totally keep.
Parkouring up to a realm of fantasy islands seems like a pretty neat thing.
And then there's Last Cave.
It's. It's just that.
A cave.
A large.
Empty.
Barren.
Watery.
Cave.
Atlantis, hnnnn.... I like that map, honestly but... No one ever goes there, and never for very long. So I guess you could get away with removing it.
Back to South Pole. As much activity as it can get sometimes, I honestly think you could replace it, maybe with some sorta realistic tundra map or something.
Lost Cave, ehhhh..... Honestly I'd think you'd wanna keep that. I mean, the original log in point was Bonfire.
Bonfire.
Lost Cave has literally no activity except for you when you log in on a new character, and it's so irrelevant I wouldn't even touch it.
That's my take on all this anyhow.