Re: 17 hmr
I like 17HMR because you can shoot it out to 100 yards accurately. My Marlin is sub-MOA at 100 yards. You can't do that with a 22LR... especially not a $300 .22LR.
At shorter distances, a .22 can perform better... if you drop a ton of money on it. As has been said again and again, .17HMR ammo is much more expensive. You can get top-of-the-line match grade ammo for the same price as a box of .17HMR (right now, at least).
I had plans to build the ultimate .17 HMR, but you are always left with the ammo issue... nobody makes match grade, so it is tough to get groups much tighter than .5 MOA @ 100, even with a perfect gun.
Now, if you have a low budget, I think the .17HMR is a good investment if you want out-of-the-box accuracy. Also, as a varmint gun, the .17 is far superior because you also have a choice of hollow points or ballistic tips, both of which give great terminal ballistics and you can reach out to 150 yards or better if you have to. If you want to keep the pelts, FMJ is an option as well.