Kangaroo pockets?

[Moondog55]

So I'm not really happy with my big red windshirt so a quick re-make is needed, adding in a largish diamond gusset in the underarm.
While I have it on the machine I think a big stash pocket on the front might be worthwhile. So generally speaking there are two kinds, the simple flat pocket with a flap and the larger style that incorporates a hand warmer pocket behind it. I've not yet made up my mind and as a general question what sort of pocket do people prefer?
If I did the handwarmer would most people do it simply with a single layer of Tricot or go all out for encapsulated Hi-Loft ?
In my case it would be Thinsulate tho as we have plenty
Preferred size? Preferred options?
An internal D-ring being a given