Its always quality over quantity for me. My favorite fighting game that isn't Super Smash Bros is Tatsunoko Vs. Capcom, and that roster only had 25 characters. Yet I was still able to enjoy the game so much and loved playing as all the characters. In contrast, Ultimate Marvel Vs. Capcom 3 has 50 characters, yet I only like playing as three different characters. UMVC3 went with quantity over quality and it really shows, why the heck is She Hulk in the game, why the heck is MODOK a character? Who in their right mind wanted Arthur as a playable character? Playing the demo/beta of PSASBR really shows that they went with quality over quantity, and I am 100% fine with that.
To clarify, 20 launch characters have been confirmed, I believe the rest PG's chaarcters will be added post launch as free content, before they begin working on possible DLC, as per the recent rumors.
but yes, I'm prepared for any out come.