Civil War Remix
This remix by Duo will get plenty of visits, I think, in part because, with its grassy slopes, it is a nice place to spend time in. With its two forts at opposite ends of the rolling prairie, it is a remix of an Unreal Tournament "capture the flag" arena, and is very faithful to it, though the NAB grass is lusher and the forts themselves cleaner-looking! If you find that there is a tunnel into a hill, but nothing to pick up in there - well, in the UT original you do find some pick-ups at the end, so maybe a revised version will add a whomper battery or two!
There has been a tendency to run a server with this map on a reduced gravity setting, which makes for fun, but it is a decent playing area anyway, with the weapons you want, but not too many of them, and the other goodies too. As with many "CTF" remixes, the playing area is large; the hills break up the "line of sight" usefully, and help keep things interesting, and generally, this looks like a good arena to look out for, either in teamplay or the usual free-for-all.
A CTF version has now been released, converted by G-MO, which, spawning-point problems with version 1.0 of Ace's mod notwithstanding, should be great multiplayer fun, though for some reason the flags are set rather closer to the stockade gates than in the UT version...