The filtration requirements for a tank really depend on the bio-load.... if you put just one small guppy in a 3ft tank, no filter and no water change also can. There is so much water volume vs bio-load that it'll take a long time for any of the parameters to build up and become toxic.
If you want to stock that tank with a good number of nice fishes, then the larger filter the better, canister filters can hold much more filtration media than hang-on filters so they would be a better choice (even better would be sump filtration, but that requires additional equipment and space under the tank).
If you have cost or space constraints, you can still use hang-on filters for the tank, just that you'd have to moderate the bio-load to match the filtration capacity. Start with low bio-load, then only steadily increase it when you can upgrade the filtration.
Its possible to have a nice aquarium without plants, just hardscape only, but you'll need to put in extra effort to remove the nitrates that build up in the tank, since there are no plants to consume it for you. So you will need to control the bio-load and feeding, and do more frequent and larger water changes to manually remove these excess nutrients.
Here are some examples of nice hardscape only tanks without plants (your main focus will be to find rocks and wood with "character"):
Photos from Google Images.
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