How should we go about our M+ comp?

So we're currently 4 ppl trying to set up a M+ comp that can reach into the 20+ keys since we want to push as far as possible for us.
We're not interested in the tripple rogue meta or 2 rogue 1 ww monk meta.

Our tank ist a Brewmaster Monk and we have 1 Rogue(Assa) and a Hunter(BM) as DPS.

I myself will be the 3rd dps but I'm not entirely sure on what to play into this comp. I'm looking at Mage or Warri but I'd play anything as long as it helps the group to reach the goal. Warri is just feeling not very good in terms of utility in my opinion. I'm down to any class or spec. I'd love to get some advice on what to play in order to help the most with dps and utility. (Except for rogue or dh tbh)

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Thank you :)