Space and installation come first. A fully recessed in-wall filler needs extra wall depth to sit flush, so check the wall structure early. If the existing wall will not take the depth, a surface-mounted or retrofit unit does the same job on the face of the wall.
Filtration: filtered models improve taste and remove common impurities, which matters if you are not confident about the building's water. Filterless units are simpler to maintain and cost less up front.
Chilled or ambient: refrigerated models suit high-traffic spots like gyms and schools where cold water is expected. Ambient models use less energy and have no compressor to service.
Sensor activation: touchless operation reduces contact points in busy environments and is now standard on most of the range.
Maintenance: filtered units need cartridge changes on a schedule, filterless units do not. Decide who is actually going to service the unit and how often they can realistically get to it.
Brand and features: Oasis, Elkay, Haws, Avalon and Sloan each offer different combinations of energy-saving timers, bottle counters, UV-C sanitising and vandal resistance, so match the feature set to the site rather than the spec sheet.