Either +Life or +Res, and -Nin. I'd lean more towards +Life, since you've already got that +40% res/+20% def aura, and to make use of that passive, you must have a huge HP pool to stay longer.

Earth main is basically always + res and - nin, because most of the time you will be using either shield standard which scales with his res or the shield passive which also scales from his res.

if you use steel body you use +life, if you use the +def/+res passive then you use +res.