These are my thoughts on the three different armor styles. It may show someone a different perspective, and someone will probably show me their perspective as well.

Heavy Armor: Seems like the best armor style, right? Not necessarily. Heavy Armor may provide the highest armor value in the game, but the armor itself can be a burden. For one, it's weighs a lot. It costs a lot of points just to carry the armor much less wear it. Secondly, it slows you down. You may need to be able to get out of something and you have no speed to do it. Of course there's a perk that lets you wear it for free and doesn't slow you down, but you have to use two perks to spend on things you don't really need.

Heavy Armor works best if you are using Two-Handed Swords and Dual Wielding two swords for an extra armor benefit to compensate for not having a shield.

Light Armor: A mobile warrior can be more fearsome than a strong one. Light Armor provides the warrior enough armor value to live through fights, but it doesn't do enough on it's own. When you're wearing Light Armor, you need a shield and know how to use it effectively.

If you're choosing to be a warrior, as long as you know the mechanics of blocking, you won't even need Heavy Armor. The blocking by itself can filter out enough damage to survive a fight with 3-4 enemies even when you're playing on the hardest difficulty.

Mage Armor: The problem with this armor is very present. Technically speaking, it doesn't exist, it's just magic on a timer. Mage armor can last between 1-4 minutes depending on your perks. If your armor turns itself off, you are almost surely doomed to die.

On a brighter note, the only people who use mage armor are mages. Mage armor is nice because you can wear your original clothing without suffering mobility or weight cost. Even so, if someone chooses to wear Heavy Armor, they can even get the benefit of up to 80% damage taken off of them while still wearing Heavy Armor making them almost unstoppable.

Anyways, those are my thoughts on the three armor types.

I don't necessarily judge armor on armor rating as much, as all of them can be crafted to the highest armor rating. I wear armor based on looks. So, I like Daedric armor. I love the demonic style of it, and it fits my Imperial's style perfectly as a Dark Battlemage, and if I were to judge it on it's armor rating, I'd say it's a pretty nice set of armor.

I agree. As far as looks go, I prefer Heavy Armor as well. The Daedric and Dragonbone and scale armor are my favorites in appearances.

Light, all the way.
Both practicality and looks.

However - not all light armor is created equal.
I find elven to be bad luck. Seems to be a damage attractor.
Glass is strong, but stupid looking.

Love leather and dragonscale. Prefer leather if choosing between the two.

There is to few nice looking light armor in my opinion only the leather variant is nice, glass looks a bit odd and the elven set makes you look like one of the Thalmor.
Using thief guild armor by lack of anything cooler.

Any armour in the game can hit armour cap without exploitive means by simply making a couple of potions and enchantments then resmithing it. Tested with fur armour +1 restoration potion (I figure one, rather than repeating it isn't exploitive, especially since I used it during the alchemy step and not the smithing step so the smithing boost is permanent), got to 747, cap is 567.

For people that don't want to level all three crafting skills, heavy armour is very good with the steed stone as well as the conditioning perk (I don't know what this is about cushion not being useful, but I've had it save my life plenty of times. I guess I'm just more reckless in my travels than most). Clearly superiour, in fact.

However, if you are willing to make it hit armour cap, light armour doesn't need Unhindered or the steed stone, it's only one extra perk and if you take it you can also get the next perk which is a 50% increase to stamina regen, which heavy doesn't get.

Heavy armour negates more damage with its final perk and also damages the opponent, but neither is actually particularly a big deal. I'd call both a waste of a perk if you don't just have one lying around.

So since all can be weightless, the benefits of each are relatively trivial and all can hit the armour cap, it's purely a matter of aesthetic taste- Which has the set you think looks best? Light armour is slightly better because of the stamina regen, but it's really not a big deal anyway.

As for mage armour... It's better to combine the armour spells with regular armour, since it has no drawback to magical prowess, you can enchant your own armour anyway, and the master level spell boosts your armour rating to the armour cap regardless of how much or little armour you have or of your mage armour perks, meaning by the time you get it those three perk points would be wasted.

Everytime I start a new character i dont know which kind of armour choose.. Heavy looks cool but it's difficult to sneak. On the other hand Light armours are less than heavy.. If i want to make a sneak character that use shield and sword too but all good shield are Heavy, so, how can i deal with it? Do I have to put perks on Heavy and Light armour as well?

Your shield material isn't very important. Any sneaky character benefits more from enchanting than any other character (except a pure mage) even, and also benefits heavily from illusion. The muffle spell eliminates all armour noise. The muffled perk in sneak cuts it in half and an enchantment on your boots cuts the other half, while the silence perk cuts all armour noise completely, making the enchantment and spell both unnecessary.

And yeah, I can't think of a single good light shield. Like I said though your body armour is the important part to invest in, the shield doesn't have a large difference in damage reduction based on its armour rating so much as shield perks.

Light armor users doesn't need a shield... I've never used one

No build needs a shield. I suggest giving one a try though, they're a lot more fun than you'd think. They're like armour you can punch people with. At higher levels you can do some interesting things with them, especially combined with sneak...

I love using sword and board for backup or fighting in general

I love using board and spell. Or just board. If we'd really gotten shields in either hand, I'd use board and board. The ultimate warrior. Shields are just the best.