Tina is the obvious choice when you look at the overall player talent. In terms of need and fit with this team, however, I think what we are most missing is a defensive, rebounding, shot blocking C type.
Uconn teams have usually been very good on rebounding and exceptional on blocked shots. This year, not so much because of several things, but a Kia Stokes type of player would make a huge difference on this team if everyone else was healthy. Stef is fine, but her passing skills have a little less value on a team that gives big minutes to three very good point guards in Paige, Nika, and KK.
Similarly Stef's outside shooting would add more to a team that did not already have Paige, Azzi, Caroline and Q. For that reason I think there are even players far down the overall list that could be difference makers on this year's team that is missing Jana for the season and Ayanna for who knows how long.
Players like Kelly Schumaker could make a significant difference on this year's team even though she is nowhere near the top of the list for former C's. Anyway Tina's overall game puts her at the top, but after that I think it would be Kia over Stef regarding what would most help this particular team.