Mark Kelly seems like the right pick to me, he’s got the overview effect and has unique experiences and leadership, already has experience in the Senate which is their main job, can probably take his swing state blue, and his seat can be easily replaced.

Shapiro is too pro-Netanyahu IMO, I’m neutral on Beshear, but his seat isn’t as easily replaceable, and losing a democratic governor would suck, and he might not take the state blue.