Most influential system (and why)

[Leynos]

No singular console tbh. Fairchild Channel F was the first to use interchangeable ROM Cartridges. Atari 2600 made it popular. NES gave us the D-Pad on consoles and many innovative series and many of the most popular series began there from Nintendo to 3rd parties. Nintendo Seal was an innovative idea. Vectrex gave gaming the first Analog stick. Genesis helped pioneer arcade quality ports to home console and from then on until they died out every console aimed for the same. Neo Geo perfected it. In Japan Mega Drive introduced the first dual analog controller and shoulder buttons. N64 popularized the analog stick and Mario 64 set the blueprint of designing 3D games around analog. PS1 took SEGA's marketing concepts with Genesis and expanded on them to help make PS1 a mass appeal product. PC Engine CD, while an add on is the first to introduce CD Rom games. DS and Wii brought in the audience that would eventually become the main demo for mobile games. SEGA Nomad well ahead of it's time influenced future systems like Switch and Switch popularized the form factor. Game Boy made portable gaming both a non luxory but mass appeal in audiences of all ages but also quality of games. Game & Watch introduced dual screens. Atari Lynx for color screens on handhelds. Dreamcast set in motion what we know as online gaming for consoles today. The first console MMO. First console with a Camera. Xbox first console with a HDD built in. Xbox live. Sony and MS would then include it in all future consoles. PS1 popularizing dual analog sticks which would become industry standard. Wii standarized motion controls in future systems from Sony and Nintendo themselves. Forgetting a few I know.