I don't know why you would need anything other than a Jester or Ladybug tbh. I've got one of each, a G-10 Jester and a ZDP Ladybug and swap them out on my lanyard every month or so and they take care of all my small knife needs. Maybe if they came out with a G-10 version of the Ladybug, I'd be tempted but right now I am absolutely taken care of by those two.
Although if you wanna go a bit bigger, the Spyderco Co-Pilot is another of my favorites. I'd recommend the MeerKat as well, but it doesn't have a lanyard hole so that limits it's use a bit. To me, Spyderco is one of the better companies for small knives because thye design their small knives as small keychain knives instead of just sizing down some of their more popular knives.
Although if you want something cheaper, then I agree with the above poster, a Victorinox is also a great little knife that can just hang out with your keys.