I like the avast marine ATO. I it's a pressure sensor tube, no moving parts, no snail trouble. I use it with an aqualifter pump.
Have one on 120g display and one on a biocube. Running 2 years at least with no maintenance, no issues.
I also have a 180g. I use a tunze osmolator which feeds into my sump. Works like a charm. Only complaint I have is sometimes if you shut it off and turn back on and the water is a little too high it'll fill to the point of making the alarm go off. You just have to know where to fill your tank to before turning it on and letting it fill the rest of the way.