Probably the Gen 1 games, because during the first times I had played them, I had never played them before, meaning I had no nostalgia towards them at all.
Oh wait, X/Y exist. Yeah...those set of games were unmemorable besides Lysandre and the few Pokemon that were really good/the Pokemon that stood out. Yeah, I don't like either, though I suppose I dislike XY more, since it's more within my time and I've had the ability to play it multiple times, if that makes sense. RBY weren't my time, XY were.
Spinoffs? I don't really play them, so I have no judgement towards them.