>>48989828>gen 1The freedom to take on the game's gyms in basically any order you want. Sure, you had to do Brock first, Misty second, Blaine after Koga, and Giovanni last, but still.
The plot not being "Obtain legendary because bad guys are doing something evil" is really great, especially compared to the future titles.
>gen 2The Aesthetics of Johto are beautiful and, while I usually hate this term, SOUL as fuck.
the Special Split was also really nice, but that's a minor thing, so I'll lump it in with stuff like Held Items, Breeding, etc. as General Mechanical Improvements.
>gen 3the Event items were absolutely amazing, with stuff like the Old Sea Map, Aurora Ticket, Eon Ticket, etc. allowing you to go and catch mythicals instead of being handed them.
The new EV system is pretty nice, since it means that Pokemon can't just do everything, but it did leave mixed attackers out to dry, so I'll give it a half point.
>Gen 4The Phys/Spec split saved pokemon like Sneasel, Flareon, and Crawdaunt, who's stats and typing did not mesh in the old system.
Also following pokemon, while not actually being that important in the long run, is very nice.