They are almost impossible to obtain with the current spawns, flanks and smg spraying.. I literally have seen nothing above the stealth chopper earned legitimately. I've seen one Warship and one Lodestar, and those were from enemy care packages.
Lol the highest I've earned is a lightning strike. I'm running UAV-RCXD-Hunter Killer. If you want to experience the high kill streaks use care package. I stole an enemies K9 Unit out of his care package :p
The killstreaks are weird in this game. They're almost impossible to obtain unless you're doing the objective, but then when you are (and are lucky enough to not die), you get them way too fast. Like say you go to capture B in dom. You get lucky and don't get sprayed down and instead kill 3-4 people. If you combine that with the points you got from taking it, you're already at 1000 points. How can they balance the streaks when what it takes to get them can vary at any one time?