Most mesh heads look very pretty. Most system heads look like a bag of smashed crabs.
Some (rare) mesh heads look amazing and unique. Some (rare) system heads look amazing and unique.
For now, I still prefer (and use) the system head. I like having the ability to fiddle about in photoshop and add 28293784 tattoo layers for subtle differences. Then again, it took me like a year to start using mesh hands and feet after they came out. Mebbe I'm just slow.