I would go with either a Penquin 330 or an Aquaclear filter. The AC would be most cost effective in the long run since you don't have to worry about replacing filter media ever month. Just get an extra sponge and rinse them in tank water bi weekly.
If noise is not an issue then the emperors or one of the best HOB filters you can get... I've tried the Emperor 280's twice before settling with a penquin 330. The symphony of motor hum (duel motor), spray bar, and noise of water trickling off the bio wheels was over powering the TV in the same room.
Penquin has slight water noise that can be greatly reduced by just turning down the flow one notch from max.
The AC is the quietest of the 3 that i have on my tanks. A single AC 500 would be all you need for the 55 gal.
As far as canisters, Ehiem classic's get my top pick. Very high quality at resonable prices. The Rena filstars come in second and are a great value for the amount of performance you get from them.
I would read through as many reviews to get a feel of what filter would best suit your needs for the price.
Good luck.