The king of Russian isekai, the Keeper of the Swords series by Nick Perumov.
The other king of Russian isekai, the Sword With No Name trilogy by Andrey Belyanin.
I'd absolutely dig a Deathstalker manga, it'd be amazing as a Nihei Tsutomu-style adaptation. (Not sure other Simon Green series would work though)
Codex Alera would work pretty well as an anime/manga, the story is close enough to light novels in plot and developments.