If you had lots of money to burn, what WW2 aircraft would you buy first?
I would buy a B-17 Flying Fortress either good to go or have one refurbished back to airworthy status.
If I had the money of Gates, Turner, or Buffett, I'd make sure to "spread the wealth" over a number of aircraft and make sure there were enough people to properly restore, repair, and maintain the aircraft I'd be garaging/using.
I'd do my damnedest to find a P40, and I'd my damnedest to commission someone to rebuild (or build from scratch) a Mossi FB Mk IV, a German 109G, and whatever non-P51 aircraft I could fine, really.