I would tend to try and do both, but if you want to keep it limited to only one of these, then my vote is for The Canadian Wonderland event.
My reasoning, although Battlecry should be a great event (now a 1.5 days long event no less), most teams at Battlecry have already competed at PARC or BTB, and thus have come to be known more or less by the Fantasy FIRST participants.
I want to see some results and scores from Canada. After all, we Northeast based mini-comp teams shouldn't have all the Fantasy FIRST fun, now should we?
That's just my suggestion though. Although, I would love to see both covered by the Fantasy FIRST crew.