I don't believe it makes a huge difference what you pick like Bart and Dave said. However, there's a few perks that work well for different challenges.
Clearly striker with shoulder charge and transfusion to get life back qork well in PvP. PvE Defender all the way for me with blessing mainly. Suppressor grenades work well if you have a good aim and I run with most armour, then recovery with agility naff all. I don't care if I'm slow, I'd rather last longer and get a few more shots off before i blow up (no out of context there [emoji6])