I personally prefer winter because in summer the temperature is unbearable, I’m sweaty all the time, there are mosquitoes and ticks everywhere. while in winter I can sleep under many blankets and be comfy. But the cons of winter are that it gets dark quickly and ice can be slippery.
My favorite season is fall. But since you limited the question to summer and winter, I say winter. It’s easier to warm up then to cool down.