Here are my favorite NPCs for each character:
Kevin - Danny - Good stats in every category and his NPC plays a role in a couple of scenarios.
Honorable mentions - Miguel - I like a few of the UBCS and USS guys, but if I had to choose one it would be Miguel. His design sticks out the most from his group and I like the scar on his cheek. Too bad we never got to see his canon scenario.
Mark - Axeman - I think it's awesome the game lets you play as one of the villain characters and his high attack stat is fun to destroy enemies on VH campaigns.
Honorable mention - Clint - Similar to Miguel, he has an interesting design and I like the idea of an aquatic-themed Resident Evil campaign. His overall stats are good too. Too bad we might never see his canon scenario.
Jim - Samuel - Probably the best stats for a Jim-type and pretty fun to play as if you can get a high crit percentage with Jim's coin.
Honorable mention - Peter - I don't use Jim-type characters a lot, but I do like how there's one in the group that doesn't have a fast virus meter. His other stats are good as well. Bonus points for having a creepy design.
George - MacDowell - George has too many doctors, cops, and civilians as NPC choices lol. I chose MacDowell for having the most interesting design of George-types and decent stats to top it off.
Honorable mention - Isaac - I have to choose a doctor NPC for a doctor character. He has the best stats out of all the doctors in the group.
David - Rodriguez - Memorable design and great stats. EOTR is not my favorite scenario, but he was a memorable character.
Honorable mention - Ben - Any RE2 character gets a vote in my book. He has pretty good stats to top it off.
Alyssa - Rita - I remember struggling to unlock her offline and was very rewarding when I finally beat DT on VH. Bonus points for having well-rounded stats in every category and she was a memorable NPC from her scenario.
Honorable mention - Monica - She might not have the best stats for an Alyssa-type, but she was a very memorable character in her scenario.
Yoko - Amelia - Not a lot of choices for Yoko, but this seems like the obvious choice as she has the most decent stats out of all the Yoko-types. Too bad she can't be unlocked by norml means.
Honorable mention - Yoko: Z - Pretty lame that the only Yoko NPC we get in the first game is Yoko in her work clothes. But her NPC is very memorable to me as she was the Yoko-type I used the most back during PS2 days.
Cindy - Dorothy - Flashback is one of my favorite scenarios and I always enjoyed Dorothy's design and backstory. Stat-wise, her fast speed and high HP is nice change of pace for a Cindy-type.
Honorable mention - Mary - I probably sound like a broken record at this point, but her interesting design makes me sad that we never got her canon scenario.