For wildlife, of those 3 the 100-400L will be the most flexible. The 70-200/4L aperture isn't significant in this application, plus the range is more limited even if you throw an extender into the mix. While the 400/5.6L will give you better quality at 400, you'll likely find the fixed focal length to be very limiting unless you have another body to hand. Possibly also consider the 70-300L if you like a more modern physical construction.
<a class="bbc_url" href="http://snowporing.deviantart.com/">dA</a> Canon 7D2, 7D, 5D2, 600D, 450D, 300D IR modified, 1D, EF-S 10-18, 15-85, EF 35/2, 85/1.8, 135/2, 70-300L, 100-400L, MP-E65, Zeiss 2/50, Sigma 150 macro, 120-300/2.8, Samyang 8mm fisheye, Olympus E-P1, Panasonic 20/1.7, Sony HX9V, Fuji X100.