5echnical enough that we can have technical discussions when needed, but not too technical to think they can do my job instead (and if they can, then stop being my manager and join me as my peer).
Why would you expect that just because someone can do your job, they should join you as your peer? That might be true for more junior folks - they have proven they are on at least the same level, emphasis on at least. What's wrong with more senior folks, who may also have skillets you don't, still retaining their tech chops?