I like the KeyWiz Max 1.5. Especially the screw in terminals, since I've yet to learn how to solder.
I made a new control panel top and once I get eveything wired again, I'm planning on testing out the Shazaaam! key function. From what I've read, it looks like I can save a few buttons by using the Shazaaam! button as a shift key. My plan is to make Player 1 and Player 2 act as Coin 1 (P1+Shazam) and Coin2 (P2+Shazam). I'll probably do the same with the Pause, Esc, admin buttons too. I think the Ipac might have the same function, so either way you go you might be able to save some buttons utilizing a shift function.