I'm just saying (and in Gen 6 terms, because current metas), but they all have their imperfections, Charizard is the most ascetically pleasing and gains a Dragon typing with Charizardite X but it's the most frail, not to mention rocks, Blastoise had been proven to be super effective vs most of Kanto and gets a HUGE. FREAKING. CANNON on its back upon a Mega evolution, but it's very slow potentially leaving it open to electric type attacks and a swift OHKO if you are not careful/haven't made it bulky and Venusaur can gain a massive speed boost in the sun and is the best special attacker of the three and when it mega evolves, it weakens its two biggest type disadvantages through Thick Fat, being Ice and Fire by half, effectively making them do normal damage and making it only weak to Psychic and Flying, which because of the current meta, are still common types today. This is not meant to ruin anyone's childhood, but I kinda based it of the meta, even then, they'd be trounced 1000 times over by even other generation's starter Pokemon, I do get that people love them cause it's their first (tbh, I feel the same with Greninja) but at the end of the day, it's opinion. I'd say Venusaur is the best of the three for the fact that it can be either super agile with the help of Charizard Y, a Ninetales or Sunny Day or the tankiest of the Kanto starters with the mega stone.