I went with a combination of snails in my tank and an emerald crab.
This is what I went with in my tank and so far am pleased, my tank is new and going through the algae cycles new tanks go through and this crew is doing a great job at keeping it clean
Nassarius snails - 1 per every 4 gallons to keep the sand bed moved around, they appreciate getting some meaty food now and again
Nerite snails - 1 per every 2 gallons
Cerith snails - 1 per every 2 gallons
Trochus snails - 1 per every 3 gallons
Emerald crab - 1 in 15 gallons
I am not a fan of hermit crabs personally, have had issues with them just murdering snails to eat them. I would rather have the snails than hermit crabs. In a bigger tank though they might not cause issues.
I bought/got well cured live rock that already had some algae growing on it so I already had food in the tank for these guys to eat. Keep in mind that if you don't have a food source for them you will need to feed them or they will die and foul your tank. I also have a lot of light on my tank so am expecting to have algae be a bit of a problem Adjust your clean up crew to your tank and what you think you will need.
I avoided turbos because my tank is only 15 gallons and even just one would not only starve in my tank most likely, but they are big and have the ability to topple rock. If you want turbos I read 1 per 20/30 gallons and make sure you rock work is stable!
I found this article helpful when choosing my clean up crew:
http://www.seahorse.org/library/articles/cucbasic/cucbasic.shtml
