I've been through a lot of different clients to try out their features. However I believe in raw mouse input and the possibility of using the anti-cheat system and who knows, maybe it's the future. I don't know how difficult it is to implement some of these things but most of them I've seen from other mods so I'm sure with a little bit of collaboration that it can be done ^^. So I'll list off some of my personal requests...
- GeoIP flags with country abbreviation
- Online verification of client, and then showing if others are using the client as well on the scoreboard (Y, N)
- Built-in IRC window
- Implementation of countless mods such as model skins, UI skins, themes, fonts, hudguns and allow changes to be made without having to restart the client by using a built-in menu
- Have important game events pop-up in the middle of the screen such as the flag being taken or returned
- Built-in flag timer for servers that just aren't up to date with flag running timers
- Full demo control, (rewind, fast-forward)
- Client-side private messaging command
- Server browser that acts like the cube server lister for detailed server view
- Music player control
- Auto verify on PSL servers
Anyways that's all I could think of!