Trochus here as well, currently have around 100 babies in a 175 litre tank, can be a pain in the butt when they get inside the skimmer pump though and also in powerheads.
I also have a couple of bumblebee snails that i have had for about 5 years.
I like to have a variety of snails in my tank as different varieties eat different unwanted things in the tank. My favorite is Ninja snails as they do a great job cleaning rocks, live a long time in my tanks, and are cool looking. Other must haves are Turbo, Nerite, Red Banded Trochus, Cerith, and nasarrius. I don’t keep hermits because they eat snails and kill each other, but I do always keep a few mithax and porcelain crabs. I don’t think keyhole do much but they are hardy and I like the looks of them, and they can get into the tiny areas in the rocks.
Mud snails. I can fill a fifty gallon drum with these in ten minutes. They are all over the place and live pretty good in a tank even though I don't have as much mud as this.
Definitely the banded Trochus. They are long-lived, can right themselves when they fall over, and reproduce in the tank. I always have babies in the sump.
Also Nassarius for sandbed cleaning/stirring. You won't see them often except at feeding time, but they are very active cleaners.
I don't have any snails...;Nailbiting. Tangs keep the rock clean and flipper magnet cleaner keeps the glass clean. When I had snails I liked trochus for the reasons others have mentioned as well as nassarius because they were entertaining to watch rise from the sand like zombies at feeding time.
For entertainment, nothing beats throwing a chunk of raw fish in the tank and watching the nassarius rise up out of the sandbed like something from The Night Of The Living Dead.
But for usefulness, turbos have done more to cure my GHA problem than anything else. You just have to be prepared to reset some frags occasionally.
I had a conch that did a great job at keeping the sandbed clean, but I think he got himself stuck in a cave and starved when he couldn't get back out. If I had known, I would have rescued him sooner. By the time I got him out, he was dead. I need to find some ceriths to take over that job -- I'm starting to get some algae and cyano on the substrate now.