The most fun I ever had as a controller was at R.A.F. Lakenheath—my first assignment after ATC Technical Training out of Keesler A.F.B. We'd get a pattern just chock full of F-4D and later, after the 48th TFW transitioned in '76, F-111E. Back then we'd jam those aircraft into the pattern so tight that we'd occasionally have to break them out to one of two VFR reporting points north of the field (Points Alpha and Bravo) and then reenter them. At times I'd have a dozen or more fighters in the pattern simultaneously. What a kick.
After that I was stationed at Davis-Monthan A.F.B., and it was a complete and utter zoo. At that time we were the busiest single-runway operation in the country, and there was no room for any kind of finesse whatsoever. The mix of traffic (A-7, A-10, F-106, C-130, UH-1, CH-53, Customs Citation, O-2, and various Boneyard aircraft) where simply too unforgiving. The slightest mistake forced us to break aircraft out of the pattern for resequencing by Tucson TRACON. That was not so much fun.
Closest I've ever seen to a midair occurred there. Flight of two Navy (why is it always the Navy?) F-8s on initial were instructed, "Break number four following a flight of two A-10s crosswind departure end, advise traffic in sight prior to break." Other aircraft in the pattern were a flight of two A-10s on base, and another flight of two on downwind. The F-8s reported the A-10s crosswind in sight and were instructed to, "Break to follow." What they had in sight were the two A-10s on base (how the heck do you get crosswind confused with base, fer cryin' out loud? not only are thy miles apart, the aircraft on those legs are traveling in opposite directions relative to the friggin' runway!). The F-8s broke midfield right into the flight of two A-10s on downwind. The A-10 lead saw what was happening and yelled out to his wingman, "ClimbClimbClimb." The two F-8s passed almost perfectly stacked between the two A-10s. From high to low it was: A-10, F-8, A-10, F-8, with no daylight any of us in the tower could see between any of the aircraft.
And then there's the occasional fatal crash involving an aircraft that you're controlling.
So, yeah, it can be a real blast, but it can also be a gigantic ulcer that leaves you shaking at the end of a busy shift. After 34+ years in the field, I'm rather glad I'm out of it.