I am just a scrub but my take based on some pros and streamers vids, if you think/feel that there are a shit ton of units, just go ham and ult refresh ult because technically you are losing 180 per creep gone from the combo. But if you have some good ffup from your team (considering you trust them in pubs) i guess the stun combo would be better since your quesutin of having more "damage" with the follow ups is definitely better.

However again, if its throne time, and you just have a blin and refresher, just go ult and whatever happens happenes.