Solve problems that you actually have.
I have been riding and commuting for a few years now. I guess commuting for at least 9 years. Seven of those years exclusively with public transit and bike. Seven of those years I did not have a car.
I bought more bikes, but that was not the solution.
Issues with winter riding:
*Can't see the road or ice that well - buy a $50 light that runs on the handlebars. This light is in addition to a light that runs on the helmet. The handlebar light provides better contrast. The headlamp provides that you can see and people can see you too.
*I get cold on my hands - buy the warm gloves and throw mitts on them. Or buy those thicker pogies for riding and have normal gloves underneath. Or buy nice warm gloves then buy cheaper pogies.
*It is hard to pedal - run on the treadmill during the winter or use the indoor trainer. Get riding tights or windbreaker pants (plus tights and other layer) instead of really stuffed jeans. Or just use a three layer system like up top, rights, insulating pant, shell (like a windbreaker).
*Scary on ice - get studded tires. get lights. choose your route.
*There is a lot more stuff to carry - get a rack + panniers and/or get a saddle bag.
Instead of buying more bikes, here is the way to achieve winter biking nirvana even in cold, dark, winter commuting in Minnesota.
Get a bike that fits in one of these categories, exemplify it in said category.
road bike - can be more racing or touring geometry
mountain bike - can be more downhill or touring
Solve problems that you actually have.
For some reason, I get distracted from solving the problem. In my quest to make riding more fun for me and do it more, I bought more bikes. That was wrong. Not because well consumption is usually the easy way out, but because I had not really narrowed down what the core issues were. People talked about how they biked all winter on these bikes, but the reason I wasn't biking was not because of the bike, it was the surrounding stuff.