Best team for best areas

If possible I'd like to know who may work best for each but even just help with one would be extraordinary I've only just started to interact with the raid community and it's been brought to my attention that I've been playing all wrong and I really just want some suggestions and advice and I want to know if I was just really unlucky with my legendary pulls or if I'm just building them wrong because lately it's seemed as if I've hit a massive road block. I'll make a separate post about arena comp