This high-performance band won't let you down. For a silicone band that will last, go with Casetify. You can sweat in it and your wrist won't get itchy and uncomfortable. That in and of itself is almost a miracle.
Over the years, Casetify has been great about continuing to sell products compatible with older electronics. So even if you don't have a brand new Apple Watch, you'll be able to find a strap that's a guaranteed fit.