Fringe is a good x-Files kind of replacement I would say and the main storyline actually gets finished and makes sense! Which I have to say is genrally a rare gem now a days. Saying that the first season is a little shaky starting really terrbly and then after the first half the writers kind of change direction. If you not seen it I recommend the end of this post to show you which episodes to start from.(SPOILERS IF YOU READ IT ALL)
breaking Bad is another good one but I assume you've watched that. Mad Men I've heard really good things about but I've not watched it though.