Pryce, forever and always.
Pryce has pretty much been my favourite gym leader ever. I'm not quite sure what made me feel this way, though when I was younger I just felt like he was a pretty cool old man, and I guess it just stuck with me. His appearance in the anime was also one I really liked, as his personality at first appeared to be the complete opposite of what I had pictured. A grumpy, distrustful, cold-hearted old man who appeared to not really like Pokémon in the slightest, untill it was shown to be because one of his childhood Pokémon had disappeared and he thought it had left him, so once he was finally reunited with it again, he began showing off his true nature.