Definitely go for the Ninja defense since you have 3. They’re great. You could even consider swapping out Heimdall for some more damage, and putting Garnet at tank.
Use a red tank at your own risk! Imo i eat them daily at a minimum of 80% win rate using
3-2 blue and purple team no matter who else is in lineup.
Raids at the diamond level are all board specific and you want to use a team that punishes a bad board and i think the ninjas achieve that, although i have a harder time with the black night set ups over the ninja ones. But that is 1 player.