Quoted By:
I personally prefer Platinum, but that might be my bias towards Dawn and indifference towards Kanto and Pokeathlon. Won't deny that HGSS has much more going for it.
BW2 also has a lot of nice content, but it's different from what HGSS or Platinum offers. ORAS is also an okay game, but only if you're into online multiplayer. If you're not, HGSS and BW2 outclass it in almost every way.
Honestly, since Pokemon is such a formulaic franchise, you've pretty much played them all just by going through one of the games. Depending on what you value, I'd recommend
>HGSS, for its single player campaign, side content, and local multiplayer features
>BW2, for the postgame and battle-related content, and non-standard (by Pokemon standards) features like phone call dates and achievements
>ORAS, but only if you like online
