I vote for the 1963 campaign. The J29 is a fun plane to fly, but I'd rather go one step higher. J34's, J32's and J35's make an excellent mix to choose from. Also, since the J28 and J33 (Vampire and Venom) are non-flyable, it takes some of the fun out of the earlier campaign.
2012 looks like fun as well, but it seems like it's more circumscribed, unfortunately, which makes it lose a bit of the attraction.
Just my $0.05 =)