I like to wear the special armors, so I say light.
It's a shame there are no good heavy special armors.
There's the Ebony mail, and that's pretty much it huh?
That said it depends on the build, right now I'm running a robes mage. I wish the Vamp armor was robes sometimes though I may swtich out to Light armor later and get some perks for it to put it on par with my current Flesh spell+Mage Armor+Necromage.
But I voted medium because I do use both.
Currently Playing: Skyrim, Fallout New Vegas, Fallout 3, NFS:MW 2012 Currently waiting for: GTAV, LR:FFXIII, Grid 2