I've always kind of hated Wattson, but that has a lot to do with how hard it is to beat him if your starter is Treecko (and Sceptile is one of my favorites, so yeah...). Tate and Liza, Fantina, Erika, Morty, and Falkner all rub me the wrong way.
Really love: Chuck, Pryce, Misty, Koga, Janine, Blaine, Flannery (WHO DOESN'T LOVE FLANNERY?!), Norman, Winona, and Crasher Wake! (the exclamation is mandatory).