Gen 4 is pretty much my favourite generation of all time.
Not because of the story because that wasn't it's strong point imo, or it's slow gameplay which I do acknowledge for it being a huge flaw and set back; but because of the Pokemon introduced (Roserade, Lucario, Giratina, Darkrai to name a few), the characters involved (CYNTHIA, Elite 4, Team Meteor as a whole, Gym leaders esp Wake and Looker for sure) And the whole map was memorable and never ending. The features the game had, the interactivity at the time, ONLINE WAS A THING, and everything else under the sun. It was just perfect for me. It was the first game I saved my pocket money to get because parents are highly against Pokemon.
The soundtrack was brilliant, I rather it than Hoenn's trumpets.
I can't fault it. There is a reason I have the timer stuck at 999.99 on my original Platinum save.