I noticed something the other day (and I promise it was really an accident) . AC is correct for the types of armor you have just like in the TT version of D&D; however, my character was "naked" for some reason (I guess I clicked her armor and unequipped it by accident while going through her equipment) and her AC was only 1 less than her leather armor. I experimented and, sure enough, she got hit or missed just as much as she would have if she wore her armor. Now, I know that some classes don't usually wear armor, like a wizard, or have proficiencies for armor (like a Rogue doesn't use heavy armor for example), but, unless the character is a Monk (and they haven't been brought into the game yet), your AC should be 0 or 1 if you aren't wearing anything at all. Gale wears robes which is essentially clothing and it is AC 10 (and bonus with your DEX modifier). Le'Zel, or any fighter with heavy armor, gets an AC of 14 (plus modifier where they apply) but when I took off her armor, she had a AC of 12 (10 + DEX modifier).
Although it is amusing to have a band of naked adventurers fighting goblins and whatnot, if you don't have any armor on (unless you are a Monk), your AC should be 1 (for d20 attack rolls), not 10.