telephoto which to use and get 500mm???

[paulbrogden10]

Sigma 150-600mm F6.3 Sport-(at 320mm your F stop is at 5.6)

Sigma 150-600mm F6.3 C (at 387mm your F stop is at 5.6)

Sigma Prime 500mm F4.5 none OS APO DG HSM

Canon 500mm is/mark2 (too expensive for me)

Tamron 150-600mm F6.3 (380mm your F stop 5.6)

Canon Prime 400mm non is (very sharp)

Canon 300mm F4 (good lens close to the 400mm)

Canon 100-400 mark 1 (don’t like the idea of dust getting in)

Canon 100-400 mark 2 (seems very good quality closer to 370mm)

Maybe I have asked this but still can't make my mind up. I can buy the sigma 500mm F4.5 in good nick for £1500 some would say considering a canon one would cost at least double its a good deal. I am also considering the canon 100-400 mk2 for a simular amount of money. What  you get clearly its f4.5 vs f5.6. I guess pros use the 500mm for a reason any advise here i just cant seem to make my mind up.

[ScottyP]

Kudos to the first person I have seen ask the same question  3 times on this forum. If you don't like the opinions/answers you received then maybe you already have an answer in your head you are just waiting for someone to echo for you. 

Go with that voice in your head.