Personally OP, as a Tank, I couldn't care less about damage, and I will always go for the mod that gives me more defense. I remember reading that 2000 Tenacity gives you about 5-6% more mitigation, and that's good enough for me, so in my many years of playing I have always melded it (since it was introduced) and I will always meld it. It all comes down to your personal playstyle, mod your gear in whatever way you desire.

When it comes to mods OP, there's no objective "right" answer, if someone tries to tell you there is, don't pay them any mind because they're most likely a narcissist & have no clue what they are talking about. The difference in stats that mods give you in general (no matter what stat you mod) are very minor, and will not have any significant effect on gameplay. Game on buddy!