>>37430723Gen IV had waaaay better level design and soundtrack than Gen III. Gen IV also introduced many, many QoL enhancements (like adding the Item Finder to the bottom screen, or the ability to monitor Friendship and Pokémon at the DayCare from the bottom screen.) HGSS had the peak deesign by adding the entire menu, two shortcuts to items, the A button and a toggle for the running shoes to the bottom screen.
Every other game has been a huge step back in that regard. The bottom screen in Gen V is utterly useless and the one in Gen VI will be once they shut down the servers. The only QoL enhancement in Gen V and VI was the ability to organize items in the Bag and exit from any menu to the overworld instantly. Gen VII has been a huge step back in every aspect both by making the bottom screen useless most of the time and by making menus that take up to 15 seconds to open while also removing the ability to exit to overworld.
Super Contests and the Pokeathlon were waaay better than the Contests. The Underground is a better implementation of Secret Bases, though it lacks battles. HGSS are superior to FRLG in every sense of the word.
Caves in DPPt have tons of items and species so exploring them takes time. They're no longer just a roadblock from point A to point B.
The only thing Gen III has over Gen IV is that gameplay is faster and smoother.