I think that the OP is looking for a standard/container based enterprise platform, so I would install both since only both provide the complete solution. I.e.

I think that the OP is looking for a standard/container based enterprise platform, so I would install both since only both provide the complete solution. I.e. install and standardize on both, but start using features as needed (of course). I.e. I would rather find out any architecture issues with istio sooner, than trying to bolt it on top of some kuberentes only app.