Assuming we are talking centerfire and not a .22, and you are looking at the best value....

The SKS. Reasonably accurate, fairly powerful, ammo is pretty easy to find, and it is Russian grunt tough. Not horribly priced, the market fluctuates depending on what's been suplused recently. I'm just not sure if you can get one in Mass.

Similiar in concept would be the Mini-30 from Ruger. Same cartridge, but it has a detachable box mag (always nice when kids are around) and more accurate, but sometimes more expensive.

In a manual repeater, Savage and Ruger both make top flight bolt actions on a budget. You don't need more than a .308 or .30-06 in southern New England, you don't have moose, but you do want something a little more oomphy than .223. The 7.62x39mm Ruger M77 would be a good choice, as would the M77 or one of the Savages in .243, if you aren't wanting the full recoil of the .308 or .30-06.

Marlin makes good lever actions if that is more your style. In 30-30 or .44 Mag, they will be fine for most anything you are likely to run into. .357 will be a little more forgiving, and you get the added advantage of being able to digest .38 with equal ease, so ammo is dirt common, but it's pretty marginal for deer.

Any of those will deal with a black bear, even if you have to hit it a few times with some of the smaller calibers mentioned.. As for a catamount, have there been any sightings in Mass yet? I wasn't aware of any south of US Route 4 in VT/NH.

I have mixed feelings on telescopic sights. If you go with one, quick release mounts and keep the iron sights on. A sling is a must have, even if it's just a shoulder sling and not a shooter's sling. If you don't know the difference, don't worry, the shoulder sling will be fine. A cleaning kit, a carrying/storage case that locks (again, little fingers) and a military ammo can with a lock kit to store the ammo in. That and a stock of ammunition that shoots well and will do what you want it to in terms of terminal performance, and you'll be good to go.

The one thing I will caution against: The M-1 Carbine. I'm going to draw fire for saying that, but let me also add I own one. They are light, handy, and with expanding ammo, fine for self and home defense. But they suck for hunting, and the ammo gets harder and harder to find every year. Even with the fastest opening hollow points I can find, it's not enough against catamount or bear, and just as marginal as the .357 for deer. Great gun, just not very good for survival.

The M-1 Garand that was mentioned, on the other hand, is hard to go wrong with if you don't mind the investment.