>>35267482DP is the one I like the most. DP had Ash be the best strategist he's ever been, and he developed custom techniques based on other trainers that he perfected throughout the saga.
DP Ash also hit the sweet spot of being competent and experienced, yet still goofy. XY Ash is boring as hell to me and feels special snowflake Gary Stuish with so many characters wanting his dick.
Finally, Paul really helped flesh Ash out by making him question his own values and training methods. A good rival does wonders.