Well my first choice would be N because I didn't personal see Bianca and Cheren as you were more leaning towards friends with casual battles, though it could be argued that Cheren gets fairly close to being a rival.
N honest was just a great personality, it was quite hard to fight against someone who had very honest intentions, clearly loves pokemon but had a skewed view of the world. I'm glad we got to be the protagonist to see through his development as person who got to see the best and worse of both people and pokemon. I think he hit on a lot of questions and morality that didn't before then get questioned much in pokemon. His quest to truly better the world(in what he thought was the best way at the time) was a breath of fresh air from a person merely trying to be the strongest or best.
However second would have to be Silver as very similarly, it was nice to see character progression through the game and honestly I do love his team as well. As a kid I always both dread and loved interactions with him as I can remember a few battles were I got my behind handed to me.