mikegreenwald wrote:
I've used the three lenses mentioned above - two by the OP, and the Canon. When I need a long lens, the Canon 100-400 II has become my "go-to" lens, sometimes with the 1.4 extender. I've disposed of the Tamron, but keep the Sigma S as an EXCELLENT backup lens, but infrequently used because of weight, and absence of the low (100 mm) end.
Most - but not all - of the time, all of them will serve well, but the Canon is the best by a small margin.