DH here. They seem pretty basic and interchangeable to me, so I just bought whatever was cheap and highly rated on Amazon, on the theory I can buy another pair if I hate them. I got some basic black Asics, and they're good. Make sure they have a draw string and side pockets. I'd suggest basic black. If you go with the Asics, note that they legs run long, which is something the Amazon comments discuss.

If you want to get fancy, but him some a Brooks NightLife gear (pants and jacket).

My DH needs some running pants for the winter. Please recommend your favorite running pants for cooler weather that aren't tights. Thanks.