I don't know how acquainted you are with Ars Magica, but given your description it sounds like it might be a perfect fit with its Mythic Europe setting!Yes, a story I run can have a lot of politicking, role-playing, social maneouvering and investigation.
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My setting is North European Medieval for the most part, with magic being known, practiced but not routine. Earthdawn might be interesting. Ars Magica I like but it's not good for mundanes.
While the default assumption for Ars Magica is a troupe playstyle you don't have to use it, if you prefer a more 'traditional' approach. Normally, each player will create a Magus character and a Companion (i.e. 'mundane') character (and any number of 'grogs', i.e. commoners, craftsmen, or guards). Companions can be Knights, Monks, Merchants, or whatever important role you can think of for your campaign.
You can also replace the Magus character with a Mythic Companion, which is comparable to D&D's Rangers or Paladins, i.e. mostly mundane characters (including Fey-blooded) with a few supernatural or magical abilities.
Stories usually involve only one or two Magus characters, while the rest of the players play their Companions. Since Magi due to their 'magical aura' have trouble to socially interact with mundanes, these Companions actually serve an extremely important role.
Typically, only if you want to have a story involving the Order of Hermes, like a Tribunal meeting will you have an all-Magus party, and the focus will be politics.
Magus characters generally prefer to stay in the background, studying or experimenting in their Covenant to improve their magical skills, learn new spells, etc. Most consider 'adventuring' to be a waste of their precious time that could be better spent poring over books or working in their labs. Also, while they wield very powerful magic, its use is rather strictly regulated by their Codex, so it takes a more supportive role and doesn't actually interfere with 'normal' adventuring. So, Magi are mostly there to deal with supernatural opposition.
So, imho, it's an excellent match. I imagine, the only problematic part would be to convince your players, especially since you'll have to translate the character concepts into Ars Magica characters. There's no simple conversion, so they'd have to re-build them from scratch.