Unreal was great single player and fun for multiplayer but there's no comparison in terms of the way the game played competitively vs Quake.

And CTF originally was from Quake 1, the threewave CTF mod by Zoid which made it into Quake 3.

Threewave: https://www.youtube.com/watch?v=nFg2PPOmA74

I believe id paid him to port ctf to Quake 2 and Quake 3.