So far it's Clemont > Ash = Serena > Bonnie. Clemont is the best because at least he doesn't have a lack of personality, Ash and Serena are tied because Ash does have great battling skills, but his lack of personality other than happy is bad. Serena feels like shipping fodder, but she might have a more shy character who's searching for a goal. Bonnie is the worst because she has a painful voice in the dub, and has no purpose than to say cute all the time, there's to depth to her at all.