Generation I: Venusaur. My friends always chose Squirtle and Charmander. What started from me picking the one Pokemon nobody wanted turned into a loving adoration for one of the best Grass-Types that Pokemon has to offer. Whether speeding around under the sun to decimate his foes with unmatched speed or sitting in place tanking hits in his Mega form, Venusaur is consistently the best of the Generation I starters. He'll always be my #1 choice.
Generation II: While I adore Grass-Types, generations II - IV took me on a road trip. Typhlosion was always my favourite in this generation, purely because Feraligatr wasn't really my style and I just had this undying hatred of Meganium.
Generation III: Sceptile was nice, but like many young children I could not resist the thrill of Blaziken. When I grew up, I grew fonder of Sceptile, but Blaziken still reigns supreme for my Gen III starter love.
Generation IV: Similar to gen II, Empoleon wasn't my style and I hate Torterra. As such, Infernape became my default favourite.
Generation V: This put me back on track for my love of Grass-Types when they introduced the coolest Grass-Type starter since Venusaur; Serperior. The elegance and sass that this Pokemon exudes is just fantastic.
Generation VI: Chesnaught. Finally Grass-Types got the Fighting dual typing. Wasn't going to pass up on that. Also, Chesnaught was just... better. Sure, Greninja was a fantastic starter, but he never quite clicked for me.
Generation VII: Decidueye continued that feeling of the sassy Grass-Type that Serperior introduced. Wasn't going to pass up on that.