I think both have health benefits. Any healthy groups I'm on or discussions with PT's I always see food suggestions with fish and chicken ... just I don't eat fish!

I just used MFP and both chicken and salmon are good protein but salmon higher fat and tuna steak is good but lower protein ... Chicken does seem to have thw highest protein and is low fat but I think if you eat fish as someone said variety is good ...none as far as I was aware is a bad choice at all I wish I liked more things to add more variety!