Sun Sun and Aquatop are two inexpensive cannister type filters I've used. They mount behind or under the tank with hoses.
They're pretty much knock offs of more widely known filters. And both SUN SUN and Aquatop seem to be the exact same filter. They're nicely made and very reliable.
I used to have an "Aquarium thing"...
Multiple Aquariums in each room of the house, etc.
These filters worked well for me.