I have had every model of mach 2made, under 500 bucks. they have all been great. the m2 is actually a stinger case necked down to 22, not a true 22lr.
they are the most fun you can have with a rimfire, a total fun time.
As far as picking a rifle goes, they are a bit hard to find new, you can find them also on gunsites such as gunbroker, auction arms, guns america, and don't forget Davidson's gun gallery, and do a search locator.
It is hard to go wrong with a cz, they are beautiful, have a great set trigger, and are very accurate. If you are going to carry it into the field, you may wanna look for a ruger walnut stock with a pencil bbl, or a savage synth stock, with a pencil bbl. I am allways on the lookout for the savage pencil bbl. However, i would not overlook anything laminate, heavy bbl, in Marlin, savage , or ruger as well. plus the ruger will come with a killer set of rings/mounts.
Most dudes who origionally had many 17hmrs, once they shot the mach2, got rid of all but one of their hmrs, and now have many mach 2s, mostly because of 2 reasons; fun factor and ammo cost. Cost is 1/3 the cost of hmr ammo.
Plus if your rifle likes eley/remmy ammo the best for accuracy, and it most likely will, these rounds are hotter loaded, and you get about 2300 fps from them, only a 400 fps drop from the hmr. Most hmr does somewhere between 2600 and 2700 fps now.
Lastly, the mach 2 will also fire the 17 aguila round, a true necked down
22lr round. it is a killer little round, fires a 20 grain fmj boat tail bullet; in either a solid point or hollow point, and it goes about 2000 fps from the
muzzle. if you like to keep game/fur/meat, this round drills tiny little entrance
and exit holes. the 17 mach 2, and especially the hmr, can leave some
pretty big blow up holes, especially within 100 yds.
Go here for more info...
http://www.rimfirecentral.com/forums/
if you go with the m2, get your ammo from online sources, this keeps the
cost to under 4 bucks a box. Such as our friends at ammunitiontogo.com.