Car flat tire question!?

well i got up this morning and my cars rear left tire was flat, jeez. so i got out my donut tire, threw er on there and then i remembered that i have all my winter tires on rims still in my garage. SO. my question here is what would be better to use for right now, the donut tire or my winter tire? i dont have time to go the a garage today to get a new one because i have to go to work soon. thanks !