User blog:Jade Nargacuga/Choosing an army

Hi, I´m new to this game so I really need help. I started reading about the armies and I found 3 that interested me:

Grey Knights

Blood angels

BA Death Company

Are they any good ? Are they competitive ?

Also wanted to know if the death company isnt that good, I mean they only seem to be compatible with dreathnaughts ab drop pods.