Since "arguement" was encouraged I've got to say a piece on the Intellivision by IntelliSteve.
I have a hard time swallowing the idea of the INTV controller being the "grandpappy" of the modern gamepads. I think the NES gamepad was a natural progression from the joysticks of old for the type of games that were played on the NES. Could you imagine playing SMB with INTV controllers? Your hand would hurt something fierce after a while alternating between the two side buttons. The controller had to be somewhat comfortable and have the buttons be more accessable. I'd say the NES Max is more of a direct relative of the INTV pad than the standard NES pad.
I look at the INTV controller as an attempt to be "something different" than everyone else at the time. VCS had sticks and paddles. Why not create a pad that one could slide their thumb around to simulate rotation and still be used as like a joystick? Odyssey2 had sticks and a keyboard. Why not combine the control with the keyboard? BAM! INTV controller. IMO, jack of all controls, master of none. I'll agree hands down that the INTV controller had direct impact with the systems of that era (5200, Coleco), but that's where it stops.
Anyway, that's just my opinion on that.