Fluval 88g 3.1 ounce Bubble Counter

I'm using one but I don't have much experience to compare with.
All in all, its cheap and works, not much more to add.

I love mine.. I have it in a 25Gallon and a 9Gallon Nano. It does the job and for the price its well designed - hang/stick to glass, gaskets to keep it all air-tight, screw-to-tighten mechanism to keep the tube connections air-tight and its CHEAP! Some people like their bubble counters mounted to the regulator rig but this is a good alternative to hang behind a rimless tank. Only once have I broken one of the connectors for the tube but that was my own rough-handling. Good thing was it was cheap enough to replace

+1 works great for me. An upright one would not fit in my stand (on a 10 lb cylinder) so I went with this one. Very happy with it.