AMBR
Metal Grandma
I was in the process of putting in a long reply this morning when the thread crashed, must have been when you were deleting the poll. 
Anyway, in short, it would be more exciting for you to go with option D to shake things up and give us the chance to see someone we haven't seen before. I doubt the festival wouldn't sell out, just might take a little longer.
That said, I'm a huge SymX fan and wouldn't mind seeing them again. I've also seen Sonata Arctica 3 times but would love an opportunity to see them at PP.
(BTW:
Anyway, I guess I'm not very helpful, because I'm really up for any of the options. It really depends on the band.

Anyway, in short, it would be more exciting for you to go with option D to shake things up and give us the chance to see someone we haven't seen before. I doubt the festival wouldn't sell out, just might take a little longer.
That said, I'm a huge SymX fan and wouldn't mind seeing them again. I've also seen Sonata Arctica 3 times but would love an opportunity to see them at PP.
(BTW:
They are in the midst of a 30-date North American tour, so obviously though they will miss some states, I wouldn't say they've toured "very limited". )Granted Sonata has toured the U.S., but I would assume it was in a very limited capacity and there must be plenty of states that they missed.
Anyway, I guess I'm not very helpful, because I'm really up for any of the options. It really depends on the band.