I brought them both to make a deciai n on which would be the perfect me to buy in the future. First off both are extremely comfortable but the flex to me seems like a better choice. It feels a tad bit better and the material used will last longer to me. After one wash of the all day gray boxer brief I noticed the material bumping up and that didn’t happen with the flex. My job requires me to move around a lot so I look for longevity and comfortable and the flex is the winner for me.