Yeah, that dilemma is hard. On one side, odds are you won't be able to play in C Division anymore so you'd lose out on the opportunity to make an epic run at the cup. On the other, returning to PAPA isn't a guarantee, so making a hard run at A Finals makes sense.
Either way, I would recommend seriously trying for Classics every day. It's a highly competitive tournament with good payouts, players, and memories. I will fondly remember scissoring my way out of finals while one shot away from qualifying. I'll also fondly remember my first NGS game being something completely ridiculous in Classics 3.