I started playing Oblivion for the first time a few weeks ago and I've been wearing the same Shrouded Armor I got at the start of the DB questline (I haven't completed it yet) some 15 levels ago.
I really liked the look of the armor you get at the end of the Arena questline but the stats still don't measure up to the Shrouded Armor so I only break it out for those weekly matches at the Arena now. After doing some investigating ... there really doesn't seem to be too many unique armor sets in the game.
I should not that I just completed the MQ so I'm waiting for my Imperial Dragon armor to be crafted. I'm also at level 25 and have yet to run across any elven or glass armor pieces. Plenty of weapons, but no armor.