Probably the greatest samurai story in anime. So much to like here and nothing to really hate until the canon material runs out.
Almost every character in RK is a practitioner of some martial art or weapon - no transformation cop outs or laser beams. The cast is full of adults with real trauma that warriors are bound to struggle with (Lots of PTSD, injuries, manic depression). There are very few kids and none of them are directing any action, which in turn helps make the fights and the story feel relatively grounded. The setting takes place in the middle of a turning point in Japanese history, and a lot of major characters have real life parallels from the period, so it can feel like you're watching a historical event take place right in front of your eyes.
There is no one way to really describe Kenshin. He is both a killer and gentle. Both lonely and surrounded by companions. He shifts in between various moods depending on the environment that either forces him to be violent or allows him the comfort of being at peace. It's that exact conflict between what he appears to be and what he actually is that drives the viewer's attachment towards him. Very human character with an inhuman ability that he struggles to suppress just like Guts and Vash. There are at least a dozen other characters I can remember that were well developed and would receive their own personal arcs throughout the story. Even the villains like Shishio had complex motivations that were justified in some way.
So long as the TV series stays canon Kenshin is an easy 10/10. It does branch away from the manga around episode 62, but the two great OVA series (Reflections, Trust & Betrayal) more than make up for that. So I'll give it a 10 overall.