Winter 100%
In summer when it's hot there's very little escape from the heat. You can strip down to nothing and still be sweating to death, shade/indoors is good but not perfect and if you don't have a working air conditioner when it's 90 or 100+ outside it's just hot and miserable.
Winter? Cold?
Bundle up, add more layers, grab some blankets, grab a warm drink. Cuddle up with people or a pet (hard to do when you're sticky and hot and don't want other body heat!), get some heat packs or rice bags and enjoy. I'll take -15 over 90+ any day, thank you very much.