Drones are the key reason why Riggers are kinda known as a Swiss Army archetype.
If you need to spy on some location, and you don't have a sneaky stealthy infiltrator on the team, send in a Fly Spy with upgraded sensor suites.
If you need crowd control, and you don't have a mesmerizing Mage, send in a Roto-drone with Suppressing Fire.
If you need an all out tank, and you don't have a chromed up Street Sam, send in a Steel Lynx.
Roto-drones are the most versatile, b/c they get extra Body to be used on customizations. So you can fit more and different kinds of toys on them than on anything else. And they're smaller, easier to handle, easier to conceal, than a Steel Lynx or Dalmation.
Duelist (or some other anthro) are good b/c you can dress them up like another teammate and bring them places where an obvious drone may not get. It's one thing to dash through a building with a miniature Abrams tank driving along, it's another to have I, Robot following you with swords or machine guns in hand.