Like:
I love Astrea snails - they're super hardy and do a great job of keeping algae from amassing on the glass.
Green Emerald crabs are also very hardy and can go through prolongued drought periods. They'll also eat some nuissance algae that nothing else will touch and are generally very friendly to fish and coral.
If you can get some stomatella or colonista hitchhikers they do a great job of cleaning tough to reach places and will reproduce readily.
Anthropods and Copepods I haven't yet reached this state, but I strongly believe that a healthy, diverse population of antrhopods and copepods is really the best clean up crew you can have. Not only will they eat softer microalgae , detritus, and leftover food but they make great food and entertainment for the fish.
Conchs - I just love these guys. They tend to be pretty hardy and they eat leftover stuff on the botton of the tank
Neutral:
Hermits - many members complain about hermits eating their coral or being general nuissances. I haven't had this experience, but have found them to be less able to withstand drought than other cleanup members. I think they're entertaining, but over time your little ones may disappear and you'll be left with one or two larger crabs. At which point it may be time to "move them out".
Spaghetti and Bristle Worms They're great at eating crud and leftover food... but who likes a tank full of worms, really...Not my girlfriend, I'll tell you that.
Turbo Snails Not much to say about these guys. They're good at eating some very specific nuissance algae (red cotton candy, some hair) but I feel like they're not as "efficient" as astreas and are a bigger bio load than they're worth. Additionally they'll occasionally knock frags over as they're big and clumsy. That said, good grazers if you don't have a thriving population of smaller snails.
Astreas not to be confused with the snails these little stars reproduce readily and presumably eat stuff... *shrug* they're nice to look at and if you have a diverse CUC to compete with them they won't overrun the tank. If you don't, they may over-run the place. Some people have reported having issues with them irritating zoas / coral but I haven't witnessed this myself.
Do not like
Nassarius / Cerith Snails I have never had any luck with these. I find that spaghetti / bristle worms and crabs will out-compete these detrivores. Every time I've added a batch they've starved over the course of a few weeks.
Peppermint Shrimp Some reefers are all about peppermint shrimp. I enjoyed watching mine too, but I enjoy feeding my coral more. Unlike the slow crabs and snails that would likely not have the dexterity to snatch food away from LPS the peppermint is nimble and will. If you only have one they will probably be shy, but if you get three or more they'll form a gang. I had them breed in my tank and when carrying eggs they become rather aggressively ravenous and will stop at nothing to steal food from fish and coral.