while i love my own maps [bayonetwork & elysium] the best just because of how much i worked on them, i have to say my favorite map by another user is... Terminal
Reflex (sorry I forgot the author lol and don't have a link!) is still one of my favorites. Most of the forgehub maps I download I'll play for a little bit then get bored. Like distortion, while definitely being a sweet map no doubt got less exciting once I figured out how to navigate the map. But yeah reflex has always been a great team-based map when i do custom games online and it's asthetics have inspired one map I'm currenlty working on.
im gonna have to say cabin favor. at it's time it was really advanced with straight walls and everything. it was the best map imo before interlocking. Tunnel rats is incredible though, must have taken forever to get the tunnels to be usable and make the helicopter.