Put your TV there. It is too high over the FP and much better beside it.

Finishing the niche space with built-in shelving will give you a great secondary focal point and also help hide the cable box and power cords. The tv could stay where it is leaving the built-ins for books/accessories/components. But you might find lowering it in the built-ins will give a more comfortable viewing angle while seated with shelving above and closed storage below for the unsightly components. Good luck!