As a whole DP was better. Ash's rivals, the storyline and the general character growth Ash went through. This is the time when people are saying he's acting like he was 13-14 and they're right. Overall he'd changed a lot since Kanto and I thought that DP really showed us that.
Preferred the Sinnoh League to the Hoenn, just because Ash used more pokemon and showed better battling skills.