>>32145249He and Dawn were pretty good friends and it was good, but they didn't have as much, I don't know how to put it, but fun moments? Like at the beginning of DP, I remember them arguing about something and that being their moment for the episodes, but the conflict felt incredibly forced and it ended in a really disappointing manner.
With Misty and Brock, there was a clear Boke/Tsukkomi dynamic that made the interactions between them much more fun, even if the character individually weren't anything special. Brock largely playing the one with common sense until they meet a girl or are traveling, where he would play the boke role, while Misty came in as the tsukkomi. Ash was always being a stupid, and gave Misty more time and reason to interact with him. Ash and Brock had a nice relationship as friends, but both were boys and kind of stupid at times, so they worked well together.
In DP, Brock had almost no fun moments with either Dawn or Ash. He was friends with them, but there was nothing else going on. Ash and Dawn were a lot better. They had a relationship like that of Brock/Ash in the beginning, without a lot of "funny" moments. That's not a bad thing, though. Just something I personally disliked.