First, pick up This Old Drone. Then grab the Reaper. Spend the extra 25% to refit it back to milspec and remove the Obsolete trait. Throw on a chameleon coating. Now you have a drone that is hard to spot, can keep flying for hours without refueling, and has four hard points for ordinance. My current favorite loadout includes an Ares MP-LMG with EXEX ammo, and three quad-rack mounts (Eurowar Antiques), one with the Azzie Iron Bomb in Arsenal, one with the Ares firebomb in MilSpecTech, and the last with Dagger anti-tank rockets from Eurowar Antiques. All of this is Availability 12 or under. Sure, it won't be much good on 'quiet' runs, but when drek hits the occilating wind-moving device, and you need to go from 'quiet' to 'loud', having this baby on standby overhead is a DAMN good thing.
Second, a Steel Lynx or similar, with your machine gun of choice and EXEX ammo. Throw on some extra armor and a chameleon coating. Still Availability 12 or under, and this one can follow you into buildings.
Third, a rotodrone of some sort, chameleon coated, and equipped with a battle rifle (and ammo bins). Makes for a very effective sniper, or as a way to distract an enemy without going full on Apocalypse Now on them with the Reaper.
Fourth, if you still have cash, grab a spy drone of some kind.
Yes, maybe I do go overboard with the chameleon coating at times, but it is easier to drive down the road with your drones in stealth mode than dealing with what the Knights say about you carrying that much ordinance through the sprawl.