I'm currently using the stealth chopper. I earned 10 kills from it the first time I used it so unfortunately I set my standards high for it. I've considered AGR but I'm not sure how durable it is. I need something between 9-13 scorestreak to use. I'm not a huge fan of an orbital vsat also.
I think it also depends on what game mode you play. I play a lot of demolition and the other day I set AGR on and got it. I drove it inside the bomb room on hijacked and just rocketed and gunned the door allowing us to blow the bomb.
From my records it shows, my agr is about 2.6 or so kills, stealth around 4, escort over 4 (per streak) so id go for the stealth any day. Plus the stealth cannot be outrun when in the open and does not show up on the minimap