He's not the most talented, not the most athletic, but I feel like he'd be my favorite ATP pro to play doubles with. He's cheerful, would keep you pepped up, and, even as a top 10 singles player, he consistently plays at doubles slams/ events and wins. He also has played with so many different partners, like Johnson, (3rd at Olympic's,) Sands (1st at Olympic's,) Pops (1st at Wimbledon,) and was (imho) the dominate common denominator at the laver cup doubles matches.