I'm almost ready to buy the genuine Nikon MB-D12 after reading many, many reviews here and elsewhere about off brand MB-D12's. I'm going to buy a Nikon. I'm having trouble deciding what battery or batteries to get. I only have the battery that came with the camera. Should I get a second EN-EL15 or buy 8 Eneloop batteries? What benefit does each battery type offer? What are you using?