i vote for the HAS Supergun (and Minigun supergun) style kick harness plug.
Playing devil’s advocate, I kinda agree with this.The HAS has the 6pin JST XH connection which is small enough to be able to squeeze in anywhere.
Besides, a full CPS2 connector is a huge waste of space. The full connector is supposed to house full P3 and P4 buttons, along with kicks for P1 and P2. I doubt people are planning on playing the 4-player games, having to deal with multitaps...and of course, having a 4P setup.
And I don’t know about you guys, but the idea of having to find or put together a female-to-male CPS2 harness sounds daunting compared to a simple 6-pin adapter cable.