I shoot with a 6D, own several L lenses, including the very sharp 24-70 f2.8 Mkii, 70-200 f4 IS and the 135 f2. The 200mm is quite sharp at 2.8, I'd not hesitate to use it here, better at 3.5 and top notch through to f8.
Very sharp; very quick autofocus; smallish; lightish; great out-of-focus blur
A little long for really good handholdability