Well, CTF is the evergreen gametype. There was an insta challange, it was enough i think. We/You should try to make a bit different. About insta, it seems free q3 based games have the same destiny(warsow f.e.)
I voted for TDM and Clan Arena(Elimination in OA, thats the name). True, there are no TDM clan. Why should be there? Everyone plays CTF and FFA But i dont think many clans would refure to participate in a TDM competition. If i had to choose between TDM and CA, i would choose the second one. The maps would be better for Clan Arena than for Team Death match. The small OA maps would get crowded fast, the few bigger ones are too open to play strategically imho.
So i voted for TDM and CA, i would remove iCTF. (And let All rockets just cause there havent been any AR tournament yet.
Edit: Most people will choose instaCTF, because they have never played the 2 others. And if they havent played, where should they know, that it's megafun?^^ (No need to answer :P)