I've used the 17HMR since it first came out but have not shot the WSM. Been shooting a Lilja barreled HMR M77/22 Mag switch barrel rifle, a CZ 452 Varmint, and these days a Anschutz 1517D HB, which is really a shooter. But for bench shooting ground squirrels and walk 'n stalk rock chucks here, my Annie HMR has connected on squirrels out past 280 yards (lasered), and to just over 200 yards on rock chucks, with head shots only on the chucks (self-imposed limitation).
As has been mentioned, HMR ammo can be found everywhere and really has quite a terminal effect on small varmints. To me at least, it also has a proven track record as long as you keep the light bullet in mind for consideration in shooting in the wind. I doubt I'll ever own a WSM. JME