i'm in your conscience
Cynthia has the better team, and I find her to be the hardest Champion of all, however I'm going to vote for Lance. I like his character much more than Cynthia's. She kind of makes you her errand runner in DPPt and that's a bit annoying imo. Making you take things to her grandmother...pssh! Go see your grandmother, girl!
Lance does his own stuff. Sure, he asks for your help, but he actually does something by helping get the password in the Rocket Hideout and then taking out the other half of the Electrode, and you get to team up with him in a battle in there. Plus his design just exudes Champion status. Not that Cynthia's doesn't or anything, but I think his says it more. It's just so regal, and matches his type. And he's really friggin' difficult in the second round fight in HGSS omg.