Recomendations for a telephoto lens for 6D

[HelenClaire]

Have read similar previous threads but as the last one was 2 years ago am wondering if there is anything new on the scene. I bought my 6D 18 months ago along with the latest Canon EF16-35mm F4L IS lens which I am very happy with for landscapes. However I do love wildlife too and am now keen to buy a telephoto but which one. I tried out the new Canon EF 100-400mm f/4.5-5.6L IS II lens at a recent workshop but am keen to look at others as well. I can see from various reviews the Tamron and Sigma are much cheaper options that seem just as good as the Canon. A previous thread on this forum recommended the Tamron 150 - 600mm, followed closely by the Sigma but that was before the newer Canon 100-400mm had come out. So am interested to hear from others as to which ones are a good buy. The Canon is so expensive so am wondering if it is worth the expense if there could be cheaper options out there that are just as good.