Well, a few weeks ago: MSR Guardian Purifier (Rock+Run and RM both had the same lowest price i could find, but Rock+Run was free shipping, even to Sweden...).
It actually appears that someone finally got water filters right: fast, easy to pump, no maintenance[1], will survive freezing[[2] and drops.
[1] Even fairly clear lakes or mountain streams clogged my old MSR Miniworks far to fast for my taste.
[2] But not if I try to pump it when frozen: no surprise, but a bit of a concern come autumn.