Filters
I have had the classic Eheims, Rennaisance, and the older Fluvals in the past. But I found that although they are more efficient and flexible, a HOB power filter works better for me. Primarily because canister filters take more effort to clean.
With a HOB, all you have to do is replace the cartridge. The canisters probably do a better job of keeping the water crystal clear for a longer period of time. But an Emperor 400 with extra carbon will do almost as well, and be more convenient to manage. I will go farther and say that an inexpensive Aquaclear will do just as well as an Emperor 400, and operate cheaper. Right now, those are the two HOB power filters that I use and they have done well for me. I have had the Emperor 400 for a year and I am only on the third set of filter cartridges.