Most relevant will be Thor, obvs! He's coming from earlier in their timeline, right at the moment Thanos snapped his fingers in Wakanda. He's kind of neck deep in his PTSD and it recently took a pretty hard blow when Mjolnir showed up in town and he doesn't think he's worthy to lift it. Also getting his dead brother's helmet as a gift wasn't exactly helpful. Anyway! When he's not depressed he's actually very fun-loving and carefree and a joy to be around. He'll be happy to see her safe.
Anyway. My other that might be most fun to be around is Gwen Stacy/Spider-Gwen from Earth-65. She'll think Valkyrie is amazing and awesome and want to learn how to fight from her. Yes.