Capacity should match the household
One cat in a small apartment does not need the same reservoir as a multi-cat home. More capacity is useful only if the fountain stays clean and the pump remains covered.
Filters are part of the purchase
Before buying, check the exact replacement filter type, price, and availability. A fountain with hard-to-find filters can become annoying after the first month.
Cleaning decides long-term use
Pump access, corners, plastic surfaces, and dishwasher-safe parts matter more than decorative shape. If cleaning is awkward, the fountain is less likely to stay in rotation.
Keep a bowl nearby
Some cats need time to accept moving water, and power or pump issues can happen. A simple backup bowl keeps hydration from depending on one device.