Always depends on what you want to do with it, for example (MMO)RPG/RTS players might need macros. Your perfect "gaming" keyboard is just your perfect keyboard in general. Also, there is no endgame.
Now to my personal characteristics for a keyboard that woild also be used for gaming:
Size: I like the layout of the TK78, I don't need the dedicated F-row for the games I play, but I use the Numpad for either buy-binds in CS:GO or being able to play GTA without having to switch layers too often.
Switch: Zealios 62g. I prefer tactile switches over linears. I don't dislike any switch, but MX Reds, i just can't get along with them.
Backlighting: RGB would be nice. Some lighting effects would be nice too, but an absolute must is either white or green backlight, if it is single color only and any different color I'm out.
So, jsut give me a RGB TK78 and I would have my dream board. For reference I'm currently using a CM QF TK with Zealios 62g and green backlight.