If you're looking for one bike to do it all, year-round, then there's no beating a fat bike. I rode a Salsa Beargrease year-round for a few years. I would also look at the trails you ride, around me there are min tire width requirements when the snow flies. You could always add a dropper and a fork to make it more "capable".
I would say if your trails don't have many requirements then a plus bike might do the trick as well.