Kalos has brilliant animation and suspense, though admittedly some of the battles feel a bit cheaper than DP due to sometimes excessive plot armour or lazy tactics ('Dodge, dodge, dodge, dodge, dodge....').
Ash seemed a little more vibrant in DP, even if his progression wasn't as well charted as in XY.
Rivalries felt more rounded, if still imperfect, in DP, a decent mix of antagonistic and friendly, with variations of competence. In XY ALL the rivalries are friendly, and few of them feel remotely like a threat to Ash's team.
Dawn while maybe not as expressive as Serena, felt more developed in goals and her progression. Her contest arc was brought in rather early and got decent screen time and what's more she was shown working and training for it. Serena's showcase arc seemed like a last minute detail when they realised she wasn't doing anything, and all in all she felt too invincible to root for. The rivals lacked screen time and only a couple could win to Serena due to what was always a fluke mistake by her than genuinely besting her, compared to Dawn who was made to accept the odd defeat and roadblock even when she tried her best, thus a need to improve her strategy.
Contests were perhaps better rounded than showcases, though despite the cliche gimmicks and occasionally bland performances, I think the latter have potential as a non-battle tournament arc and could often be entertaining, especially due to the animation bump.
Clemont while not getting a lot of arc development, still seems more vibrant and important than what Brock was by the time of DP (though at least got something of a decent finale).
Team Rocket were badly flanderized in DP, though did at least get some decent spotlight episodes and hidden depths (this was the start of them being allowed to win things for example). XY Team Rocket are more subtle and competent, however, while they do get a decent amount of depth and limelight, they often feel very much like filler to waste screen time.
Dubbing was hit and miss for both. Some of the dialogue in English DP was atrocious (especially for Team Rocket) but the music was possibly at it's most loyal, with a lot of episodes the soundtrack stayed completely the same. XY has more loyal translated dialogue par the odd bad line, but omits nearly all the soundtrack for bland elevator music. Both regions have a ridiculous mood killer.