As Bruce M says, stay away from galvanized and vinyl. I suggest seamless, aluminium gutters. I used to live in Fr. Collins, Colorado for 6+ years and am familiar with its snow. Even when it snows a lot, it's usually dry (light; not heavy like it is in the NE). If you're on the Front Range but not up in the mountains, my recommendation remains the same. If you're higher than 7000 feet, this could change.
I'll assume that the installers out there know about snow, its weight, and the propensity for it to damage your gutters or your roof line. You'll have to trust them when they tell you you should use XYZ hangers because of the type of snow you get.
And lastly, it's not enough to simply install gutters and downspouts. You need a place for the water to go when it comes out the downspout! Do keep it away from the home. If you have to run 10' of straight pipe to keep the water away from the home, I suggest you do so. And the next time you reshingle your roof, ask for drip edge ALL AROUND; not just where you install gutters. NOW, when they do install your gutters, do ask for drip edge for them. And lastly (I know, I know), if possible, if where they're going to install gutters is wood, I'd clean (always clean), prime, and paint with a good primer and paint first. Spend $25 a gallon because you'll only need a couple. If this wood is rotting now, you'll have to remove your gutters to repair it. Do it now before the gutters are installed. And better yet, if they can 'cap' the eaves with alumium too, I'd consider that.
Best to ya and I hope I haven't swamped you too much.