If best way is the only...why do we see different setups ?

[AlphaSonic]

Well AST has an explanation.

AST 3.0 was terrible, was the worst healer by far.
In 3.05 and in 3.07 AST got lots of buffs (and even now Nocturnal AST is still bad compared to their counterpart).

By 3.07 everyone had already spent their Esoteric and people weren't going to roll again AST because it would have mean losing their Esoteric Weapon.