>>41216526>CrystalOnly played this as an adult, but a straight upgrade to GS. Animated sprites still look great to this day. Battle Tower was a very cool addition, and lines up nicely with the Pokemon Stadium games. I'd go as far as to say that it's the first Pokemon game to have felt "fully featured" by modern standards. Would be a top pick, if not for HGSS.
>RSFun, but contentious. Even as a kid, I missed the day/night cycle, and the decision to exclude a significant amount of Pokemon on release (RS has what, 200?) including a lot of favourites was not well looked upon. Most heavily story-focused up until this point, which was a breath of fresh air in 2003 but has gone on to become one of the series' least liked features. The puzzle to find the Regis, and the sense of mystery surrounding this ancient society which has tried to keep things buried, is still probably the best side quest/legendary hunt in the series. Hoenn is a cool region, but these games were let down by some poor decisions.
>FRLGStraight upgrade to RBY, with some nice additional content in the Sevii Islands (1-3) and post-game story (4-7). Among my favourites in the series, since you get to explore the best layed-out region without any of the gen 1 stink attached. Also worth noting that these were the first games to have an Elite Four power-up once you rematched them, which I always loved as a kid. A top 5 pick, for me.
>EmeraldStraight upgrade to RS, and the best in the series up until this point. Points in its favour such as the Battle Frontier, higher availability of mons (post-E4 Safari Zone) etc. are all obvious. If you liked RS, then Emerald is just amazing. In my top 3, for sure.