Premium Team Or More S6

I’m in a dilemma regarding my next pulls. My Luuk Herssen is already S6, but my current team is still the 'budget' version (Luuk + Sanhua + Verina).

Should I go for the full premium synergy by pulling Denia + Mornye (with signature) to finally complete his best-in-slot team? Or is it better to go for S6 Carthethyia, knowing that she’s a top 3 unit who can basically solo any content at S6 without needing a team?

After seeing Denia’s kit, I’m stuck in a dilemma between having a premium team or roster diversity. Currently, I can easily clear ToA and Whiwa with my S6 Luuk and S6 Zani, but because I lack team diversity, I’m struggling to get all the rewards from the End Matrix.

Should I complete the premium Luuk team (Denia + Mornye) so both my main DPS have a premium team, or go for S6 Carthethyia to help carry a separate team solo?

extra noted: I have like a HUGE skill issue that why my investment since this game lunch is having as much s6 DPS in my roaster but because of this decision as I mentioned I'm having a really really hard time fully clearing the end matrix content