I liked most of the Unova rivals taken on their own, but they never really made a complete package the way they did in Sinnoh. I think Ash's Unova rivals were all too similar. Bianca and Cameron were basically the same, inexperienced, scatterbrained trainers who rush into things and don't think things through. Stephan showed himself to be a little more composed, but was also inexperienced and battled very straightforward. It's basically three Barrys minus the interesting dynamic with him emulating Paul. Virgil was pretty much just there to tie things up in the Unova league. Trip had an interesting story but the big problem with it was it had nothing to do with Ash, it was really wrapped up in the battle between him and Alder. So these rivalries really lacked any intensity because there weren't really any conflicting personalities. It was an, 'oh well, I lost, but I won't lose next time!' type deal.
The Diamond and Pearl rivals tested Ash a lot more than any others really did. Paul obviously was an awesome battler who really punished Ash early on for his loose battle style, forcing him to tighten up and battle more conservatively. Barry was interesting because on paper him and Ash are somewhat similar, but in reality Barry's desire to find stronger and stronger Pokemon clashed with Ash's idea that any Pokemon can be strong. The two were on good terms with one another but still had something to prove. Conway was a pure theorist who came up with brilliant strategies but couldn't adjust went things didn't go his way. Again, despite his creepiness Conway was still a pretty nice guy, but he had a different way of looking at Pokemon that clashed with Ash's ideas. This made the battles between them all the more interesting and intense.
