Standard runes are Grasp of the Undying since it synergies well with K'santes kit. The more HP he has the shorter the cooldown on his Q. And having cheapshot as your secondary runes, as K'sante you'll be able to immobilize your enemy more easily because of you Q, W, and R. Shield bash is a good pick for K'sante since you'll be using your E more than you would think. K'Sante has a lot of mobility which is why you don't really need to rush boots first.

And about the conqueror runes.

If you're feeling confident about playing as K'Sante. Your main source of damage will be coming from your Q since it has AD scaling. Scaling that isn't based off of your Bonus AD but scaling from your total AD of 40% I think. Yes you won't be as tanky as the other builds but you'll be more focused on damage than tanking hits. So it's best to play safe in the laning phase unless you know you're a better player than your opponent.

And about the build for the tanky version.

heartsteel is currently the best items for tanks such as K'Sante in this season. And it will give you 5% bonus HP when you are full build. It's a really strong item for K'sante and the second Item is Titanic because that'll be your only AD item. Since Titanic will give you more AD based off 2% of your bonus HP. So you don't need to worry about building other AD items and focus more on the items that gives you more resistances or HP.

And for the AD Bruiser build.

I chose Divine Sunderor as a mythic because the passive when you proc it. It'll act as your Grasp of the Undying since you'll be using the Conqueror runes. And like above, Titanic will be your second items because it gives a lot of HP and a decent amount of AD for your Q. And since you'll be playing as a bruiser, you'll be building a mix of AD and tank items which will go well with his Q.

And if you like this build, give it a thumbs up and if you have any suggestions. Feel free to discuss it and give your opinion. I'll be reading your thoughts and opinions.