I've been watching quite a few Let's Plays on Youtube and I find it so funny how the let's players character look really badass but their follower is always dresses with the most random equipment. So I was wondering what your "go to" look for your followers is. If you had to pick one.
I think I'd have to go with an Ancient Nord Set, my characters are always squishy and always use necromancy so having an Ancient Nordic warrior with a ridiculous amount of HP following me around during the day just fits perfectly.
I think it depends on the follower's class. If they use magic, I like to have them in robes, warriors get heavy armor, and sneaky ones get something light. But I have found that most of my followers look really good in Orcish armor, and Khajiit look really good in Nordic Carved. :P
Ditto what Xeelus said about class. It depends on what they're skilled in. There are a few mismatched ones though (e.g. J'zargo is a mage but is proficient with heavy armor, so he gets heavy armor--I like him in enchanted Nordic Carved).
If it's appropriate (my character and my follower have the same armor skills) I'll put us in matching armor sometimes. Just for fun. I like the whole team thing.
Basically this, but I'll also add that I rarely give my followers helmets. I like seeing their faces just so I don't feel like I have a random person following me. Besides being in cities/buildings with helmets just looks silly to me, and I find it to be too much of a pain to just taking their helmet off everything we enter such places.