I've had one of each, and I think I prefer the winter, although I know that there are those who don't. I didn't find that the extra bundling, etc. was too much of a hassle, and it was a kind of nice cozy time to be at home. We didn't feel like we should be heading out to the park or the beach, or anything, which was great, since I didn't have a whole lot of energy for extra things at that point! (Who does, either right before or right after birth?!)
I imagine there are good sides and bad sides to both, and I'd say just try to look for the advantages of what ever season your baby is due, and enjoy it!
All the best!