Marquez Callaway

It should be

MT
Olave
Harris
Callaway

As your premier group. Harris runs really crisp route that Callaway can't do at the moment. His curls are absolutely ankle breaking on DBs. He just got a limited catch radius and nullified if he doesn't have the proper inside leverage to the ball.
It will be situational as I implied. You're not going to get blocking from Harty or Olave, so you will need a different WR in many sets where blocking is required. A 3 WR set consisting of CGM, Harty, and Olave will be problematic from that perspective. There won't be a "premiere" group. Just situational sets depending on what the Saints want to accomplish on that play.