Master Xanthan
Smash Champion
I guess it would be inefficient to use Harrier Airstrike/Chopper Gunner/Nuke all the time. But I still want more nukes so I"m probably gonna stick with that for a while. When I decide to stop trying to get nukes I'd probably use Predator Missile/Harrier Airstrike/Chopper Gunner. Sentry Gun isn't too bad either but you need to put it in a good spot for it to work well, plus someone can just run behind it and knife it if they've killed you already..I got the n00ke once. I think it's stupid to run around with that as your killstreak all the time, as you basically lose a killstreak, in exchange for ending the game early, which is boring as hell anyhow.
Predator Missile/Harrier Strike>Harrier Strike/Stealth Bomber>Chopper Gunner
That's the way I do it. Stealth Bomber is 100% **** in hardcore.