I generally don’t use many upgrades, but there are some that are really good and some that are a must.

That being said, which do you think is more important, including an extra unit (with heavy) or having the following upgrades: Force Reflexes, Force Push, Improvised Orders, Medical Droid, Duck and Cover, Emergency Stims?

The named upgrades were on my Commanders/Operatives making them much harder to kill, but Im thinking of going with the extra unit (with heavy), giving me another firing unit over greater survivability for my Commanders.

Depends on the commander/operative. Force Push and Force Reflexes are pretty essential on Vader or Luke. Improvised orders is pretty hard to pass up as well if you have the opportunity.

I think duck and cover is only really worth it on units with danger sense or low profile.