I do allot of rimfire shooting, strictly IMO, the .17 is more accurate than the WMR because it gets to the target faster, therefore less time for the shot to be disrupted, like wind and so on. The 17HMR is good over the WMR where noise is of concern, it has a very light report, however, the tiny .17gr rounds don't perform as well as the WMR. Ive seen it recomended time and again that it's suitable to game smaller than a jack rabbit, but I've taken a coyote with mine...shot placement is critical, in this case I was able to put the round in the "yotes ear at 125yds, I wouldn't bother trying a broadside on one. I think the 17's popularity just caught on from the accuracy aspect, as well as being a neat little round. As for the Mach II, fast, but thats it, it didn't really catch like the 17HMR. Sure they're nifty for plinking, but no more enjoyable than the plain vanilla .22lr, nor any real advantage. I personally can't say that I have an advantage with the .17HMR over the WMR, funt to plink with, but theres super accurate WMR's out there along with the 17HMR's, my machII is fun also, but again, no real advantage over the .22lr. I have several firearms chambered for the rounds discussed in my post, so just my .02