NES, GB, SNES my parents bought for me early on in my life.
SAT - from playing arcade games such as Daytona USA, Cyber Troopers Virtual-On, Virtua Cop & reading upon SEGA's upcoming 32-bit home console wanting to play Die Hard Arcade (which was an exclusive game) sold me overall.
PS1 - from playing Trap Gunner, Ghost in the Shell at my friends house. But ultimately what sold me was wanting to play (ironically) Dragon Ball GT: Final Bout, and Twisted Metal which were all exclusives.
DC - from playing arcade games such as Marvel vs. Capcom, Power Stone, Street Fighter III: 3rd Strike & reading upon SEGA's upcoming 128-bit home console wanting to own Tech Romancer (which was an exclusive game) sold me overall.
PS2 - from renting the system to play Zone of the Enders and having the DVD functionality included.
GC - my parents bought this system for me as a gift. Enjoyed playing Capcom's Gotcha Force the most.
360 - the overall price of the Arcade version and wanting to play WarTech: Senko no Ronde.
PSP - wasn't too interested overall, but what sold me was Gurumin: A Monstrous Adventure.
NDS - the overall price of Lite version and wanting to play Mega Man ZX.
GEN - owned this system much later in life but played it as a young one at my friends house years ago. bought a Everdrive and dove into the catalog. what sold me was Treasure developed games such as Gunstar Heroes, Alien Soldier and others for example.
TG16 - owned this system much later in life and around 2015 bought PC Engine with a Everdrive and dove into the catalog. what sold me was (ironically) Bravoman, and Bomberman '93.
TGCD - included as Interface Brief-case Unit decided to start buying Japanese games with playing occasional back-ups. what sold me was Kaizō Chōjin Shubibinman 3: Ikai no Princess, and Star Parodier.
3DO - owned this system much later in life and around 2020 and dove into the catalog buying physical games and playing occasional back-ups. what sold me was Guardian War, and Lucienne's Quest.
PS4 - wasn't too interested overall, but what sold me was Street Fighter 6, The King of Fighters XV.
WII - owned this system much later in life around 2020 started buying physical games. what sold me was (ironically) Nights Journey of Dreams, and Sin & Punishment: Star Successor.
WII U - owned this system much later in life around 2020 started buying physical games. what sold me was New Super Mario Bros. U and New Super Luigi U.
NSW - wasn't too interested overall, but what sold me was Super Bomberman R, and Super Mario Bros. Wonder.