I have used Aquaclears on my nano-reef tanks (up to 20g) with tremendous success. I had an Aquaclear 500 (now 110, the biggest model) on a 20L reef tank, where I took all of the media out, glued in a baffle, and used it as a mini refugium with Chaeto algae, live sand and a few pieces of live rock. It was excellent! The flow is great, and they are quiet and reliable.
But, with my current planted tank, i wanted to find out what all of this buzz about Ehiem canisters was all about... So, I'm running an Ehiem 2215 on my 29g presently. Absolutely, hands-down, the best filtration method iIve experienced to-date. Not only because it's a quiet workhorse and requires minimal maintenance, but also because it provides so many other options like an inline heater, inline atomizer, and a wide variety of input/output options that are far more effective and aesthetically pleasing than a HOB, Sponge, UG, etc.
I've also had experience in the past with Penguin Emperors which I liked, though I think I'll be a canister guy forever now. I've also used UG filters, but god do those suck. Cumbersome, inefficient and down-right ugly.