It's not so much that this is the best Pokemon game, it's that it's the least flawed experience.

>Gen 1, the origins. Great monster design, doesn't hold the player's hand, well designed region, story doesn't bore the player by saying more than is necessary. Not made well, but makes for a good experience.
>Gen 2, the expansion pack, is fucking boring and doesn't have enough focus on the new. This starts the shift to competitive Pokemon as a focus. Kino atmosphere doesn't save the boring experience.
>Gen 3, the first soft reboot, with the awful music and crap monster designs. The soul is gone, merch, merch, merch.
>Gen 4, a forgettable generation with even worse monster designs, abysmal pacing and woeful dungeon design.
>Gen 5, where the Story Tumor problem of Pokemon comes to full fruition. Dreadfully boring with too much dialog no one cares about. Ugly game that is too ambitious for the system it's on. People complain about the monsters, but the plot content of the game is the real issue.
>Gen 6, clearly unfinished and having no impact. Boring region with little to do.
>Gen 7, the Gen 5 redo with endless boring dialog. Added to this, game thinks you're retarded because GameFreak blames the consumer for their shit dungeon design in Gen 4, not themselves.
>Gen 8, the worst and least memorable monster designs of all. Massive amounts of cut content. Clearly unfinished.

Guys, we need to accept it. They shill Gen 1 not because Gen 1 is a magical perfect game, but because they ride on it's success. They haven't done anything close since.