A well filter has a harder job than a city filter. Iron and manganese arrive dissolved and invisible, then turn into rust and black slime once they meet air. Hydrogen sulfide gives the rotten-egg smell. Bacteria are not a filtration problem at all: they need UV or disinfection. The five systems here take different routes: air injection tanks that oxidize and backwash (SpringWell WS1, SoftPro Iron Master), cartridge housings with an iron stage (iSpring WGB32BM, Waterdrop WHF3T-FG), and a carbon tank with a UV chamber (Aquasana Rhino Well Water with UV).
The number that matters most is the one on your water test. The SoftPro Iron Master states up to 30 ppm of iron, the SpringWell WS1 7 ppm, the iSpring WGB32BM 3 ppm, and Waterdrop and Aquasana state no iron limit for their models. Buy below your iron level and you will be changing cartridges every few weeks, or staring at orange laundry anyway.
With our well water weights, the SoftPro Iron Master ranks first: the widest stated iron range, nothing to replace on a schedule, a lifetime warranty and a 6-month money-back guarantee. Two of its criteria are left out because SoftPro does not publish a service flow or a media life, so read its review before you decide. The iSpring WGB32BM is the budget answer for moderate iron (up to 3 ppm) at $536, and the SpringWell WS1 is the tank to look at if you want a stated 12 GPM and sulfur handled in the same unit.