Need Help On Armor Replacer Moding

[additc]

I want to create a mod that replace some armors with customer armor. For example replace Imperial armor with Tera so all guards in Solitude will wear Tera armor. Please correct me if I'm wrong, I realize there are 2 ways to do it, one is replace the Imperial armor mesh & texture itself so it actually become a Tera armor. Second is change in CK so all guards wear Tera armor instead of the orginal one.

 

Assume I'm going to do a lot of armor set. May I ask which one is easier and is there any tutorial you guys can share? Many thanks.