Battle Angel Alita by Yukito Kishiro. started to read it back in the 90's, still reading it ( Mars Chronicles ) plenty of good ideas and designs. Sechs in Last order is one of my favorite manga characters.

When it comes to ancient Japan/Samourai theme, yes I like Blade of the Immortal but my favorite is still LONE WOLF AND CUB by Kazuo Koike Goseki Kojima. The art must have somewhat influence Frank Miller too. For good reason.

and lately being enjoying too much One Punch Man by ONE/Yusuke Murata. I was reading online the original version by ONE, crappy art, but all the flavor was already there and Murata ( EyeShield 21) with his unique style really created the perfect storm.

...Just the premise idea that the manga starts with a mighty powerful and bored hero instead of the classic Shonen promising motivated hero says it all. And you want to see where the manga will go. Here are a few comparisons from original ONE manga to Murata version.