I love Hoenn, it was my first region, and it introduced so many things, which mainly all stayed in some way proving Hoenn had good features. Time, sure G/S/C did it but FR/LG didn't keep it everything else did; Pokeblock, turning into poffins, and later that Pokeathlon juice, maybe more pokefoods I''m forgetting about xD; contests, turning into Pokeathlon, turning into musicals and eventually Pokewood (I think it's called xD)
Hoenn also had cool places to go, Mt. Pyre, Underwater, Safari Zone, etc.
To me Hoenn never gets old, and I replay it all the time with new challenges.