We don't get much if any snow around here. They only salt overpasses or bridges if the snows hangs around at all. Otherwise it's gravel or your studded tires. So no rust issues really.The envoy was in an accident the trailblazer wasn't or at least it wasn't reported as being in one. I didn't see the type of accident, that would be my first concern. The milage isn't that big of a difference. Most of the vehicles in my state of that age are rusted to the point of being worthless, at least it doesn't seem you need to worry about that.
Leary of the reported crash for the Envoy, but can't see any damage in the pictures so makes me think it was professionally repaired. Add that to the bus ride just to get it, I think the Trailblazer will be the one.