Most influential system (and why)

[Zippy6]

Soundwave said:

HoloDust said:

- Atari 2600 - for making interchangeable cartridge format popular (Fairchild VES/Channel F being the first), thus making software business on open (non-willingly, since they lost in court to Activision) hardware platform (for all the good and bad) a viable option, effectively kickstarting 3rd party developer console industry.

- NES - for popularizing D-Pad (no, Nintendo didn't invent it, it was Tiger Electronics) and making it standard for consoles, as well as for introducing "Seal of Quality" and all the related restrictions, as different type of approach to 3rd party developer business model that managed to return fate in home video games to NA market after the crash of '83

- OG XBOX (AKA Dreamcast 2)- for being first console to have architecture that will set the blueprint for how consoles are built in later generations, introduced HDD as standard, thus opening console market to more demanding games, as well as for making first unified online gaming experience via XBOX Live in console market.

I feel it's a bit too soon to tell for any other console after that.

Pretty sure the Nintendo Game & Watch introduced the d-pad, not Tiger Electronics.

"In 1979, William F. Palisek patented the first true D-pad design for Tiger Electronics. His version featured a single piece of plastic resting on a central pivot and four directional switches that provide input and keep the plastic pad resting in a neutral position when not in use.[5] Tiger debuted the design on its Deluxe Football with Instant Replay handheld in 1980"