Actual hard points to intelligence and vitality increase your pool(s) and give you defense.
You need Strength or Dexterity items to increase your damage output outside of Enhanced Effect.
I solo hardcore all the time (used to everyday), I am a Guardian freak because of the Intelligence and Vitality being higher
than the rest of the other feeder classes, also, I prefer the healing aspect of this build as well to help with higher chances to
survive. Only problem is that this class has more restrictions than the rest. Lately I use base 90 vitality / 75 intelligence and
rest to damage stat dependent on weapon.
Go with what you prefer, but if I wasn't a Guardian, I would go with 75 minimum Vitality.