Honestly, all of the DS games are good. You may want to skip DP and just go to Platinum, since Platinum added a lot to make the game better. DP doesn't really have any advantage over Platinum unless you want Stunky or Glameow or whatever.
Be glad you can't play RSE. Terrible games.
Emerald isn't a bad game. I played all gens, and I have to say Emerald is my favorite.
On topic: PMD sky is a really great game, my favorite game even.