I voted Other, mostly because I want to be specific about something.
I am fine with Wizards having penalties for wearing armor, so long as these are the penalties of the same nature as what every other character has to suffer for wearing heavy armor. A mage wearing armor should have the same advantages and disadvantages compared to a mage without armor as a fighter with armor would have when compared to a fighter without armor.
I don't like the idea that there is something inherent to armor that affect wizards in particular. However, I am a bit more open to the idea that iron affects magic, so long as it is something that is setting specific, clearly laid out, and done well.
The one time I have seen the opposition between iron and magic done in an interesting way was the videogame SaGa Frontier 2. In that game, iron or steel weapons and armor severely weaken the magical abilities of a person equipped with them. However, this is in a framework where the use of magic is the dominant form of battle in the world, so almost every last character in the game is a hybrid fighter/wizard (and many of the best attacks in the game are hybrid magical/weapon arts). What is more, it is a setting where all magical power is drawn from your equipment. Characters must use wooden staves to cast magic related to plants, bone knives to cast magic related to fangs and beasts, stone axes to use earth magic, etc. Because of this, pretty much everyone uses weapons and armor made out of just about everything except iron or steel. Warriors who use iron and steel gear tend to be very rare elite soldiers, rather than the default. And because of the way the game's equipment system works, even carrying a steel weapon with you is enough to get a severe penalty to your magical powers, even if you are using a powerful magic weapon at the time and are keeping the iron weapon on your back. Of course, iron and steel weapons and armor are far and away the most powerful, durable, and expensive pieces of equipment in the game.