Here are some thoughts, and they're probably worth about as much as you're paying for them! To give you some context for these thoughts, I have a Montgomery 15 (not 17) and a somewhat larger, much heavier, Vancouver 25.

It's sometimes hard to define "better", and this seems especially so with sailboats. It's really a matter of what is best at doing the job you want it to do. Having said that, one of my boats (Dolphin) is clearly unsuitable for the purpose that I bought her for -- except that as soon as I saw her, I knew "this is the one". What does this mean? Dunno... Probably just "buy the one you want". There is no rational, practical reason to own a sailboat, so the only way that it can make sense is if it gives you pleasure -- and that is subjective.

It's a pity that we focus on length (usually SLOA -- defined as sales length over all) as the defining number for a boat. I think that displacement (weight) is a better measure, and this puts the Hunter (I assume that you meant the 212) at 1800 pounds is actually not much bigger that the M-17 at 1600 pounds. To give you another example, Dolphin at 25ft LOD (length on deck) weighs 7000-8000 pounds, while a Hunter 270 is probably a foot or so longer but weighs 5000 pounds. They're designed for different jobs: Dolphin was designed to take two people anywhere in the world, while the Hunter is designed for a family to go sailing. Which is better? It depends.

I just saw some Hunters at the Annapolis show, and I can tell you that they are absolutely, positively not as well designed or well built as the Montgomery. No question. Not in the same league. Does it matter? Well, the Montgomery will last longer and be easier to look after. It has the potential to give you more pleasure just by existing. The Hunter might (I'm guessing here) have more room inside, but (guessing again) the M-17 will have "better" space.

As to where they can be used... Don't know about the 17, but I know that a 15 has crossed from California to Hawaii -- and I'll mention here that the Great Lakes can be as threatening as most places outside the Southern Ocean. The Hunter uses water as ballast, which is a great idea in some ways but (IMHO) has some serious drawbacks.

You might want to consider a used boat. A new boat salesman will tell you something like "there's always something that needs fixing on a used boat", and he's right. But he forgot to mention that the same thing is true of a new boat.