Ebony is my personal preference but Stalhrim is pretty cool too.
Ebony is a nice goal, I think, though it is more an armor I'd associate with lords and such. Steel plate is a cheaper and more easily forged suit of armor, though of notable quality(can reach armor cap with normal legendary quality + perks, no exploits needed), which I find to be a more likely choice for mercenaries and such. But that is just how I see it. Which armor you want to use is, ultimately, up to you.