Ha! That is a trick question!
The BEST foundation is whatever you like to use best.
My best foundation is whatever is cheapest and easiest, at this point it is the PF100 all plastic frames/foundation. Nice straight combs that last forever, well at least the foundation....
Close second best would be plastic in wood frames, followed by wired wax, then foundationless.
All drawn plastic sounds nice but as with all plastic frames there are acceptance issues. Never tried it.
I'd actually recommend trying all of the above if you can, although mixing plastic foundation and wax foundation can be trouble.