[rwest]

I have no experience with either of those, but have dealt with a couple different types in a commercial setting.

A quick search seems to show that the Aprilaire uses a replacement canister and the Honeywell has a tank and coil.

From my experience take the canister version as boiling water leaves behind a lot of junk and is a pain to clean off of a coil version and the impurities in the water when heated also tend to eat the stainless heating elements.