KG.
No question.
A 28 yr old All Star PF, a 26 yr old All Star PG, two 30+ former All Stars still playing at a high level.... Cs would be instant contenders, not just this year but for the next 3+ years, and a destination spot for all big name FAs. Of course, since we'd have to give KG a max deal, that would limit the amount of other money we'd have to spend....
But that would be a good problem to have.