Canister vs. hang-on-back (HOB) filter: which should I buy?

Across specialist communities like r/Aquariums and r/PlantedTank, the consensus is that canister filters offer far more media capacity and biological stability, making them the preferred choice for larger or heavily stocked tanks, while HOB filters are cheaper, simpler to maintain, and well-suited to tanks under 40 gallons. Several community reviewers note canisters keep equipment clutter out of the tank but cost more upfront.