One of the best 1v1 maps I've played on is called
Greenhouse by Zanno from the MLGpro website. He's done some amazing forging on Ghost Town and has made an excellent gametype to go with it. Actually, I'd recommend using the gametype for
any 1v1 game you play.
AMidgetAndAClub made
Archetype, which is another good one despite some trip ups here and there in the geometry.
bnasty574 made a great BR warmup map called
Axis. He has his own gametype for that.
I'm quite sure there are others, but I can't think of them right now. Lastly, I'll humbly submit to you my 1v1 version of
Radius. I based the weapons and powerups on Zanno's gametype, and the map really plays well in a 1v1.
If you're interested in a long, informative read on the best 1v1 settings and why you should skip playing Guardian, read
this.
Hope that helps you.