Precedence of 1,2 carbocation rearrangement
The obvious order is via the stability of the carbocation of the group.


I think you meant the migrating groups stability?
This is not what textbooks say.
Reactions are ruled by the $ΔG$ of the activated complex. 
This may be close  to educts, or to products, or some halfway 
state or a real intermediate minimum is on the reaction path. 
So, in some cases the model of a separate carbenium ion 
(in a ionic pair maybe) is useful, sometimes you need to 
think of a three-center bond state.