What is your favorite fighting style? And what experiences with the various styles have you to share?
My favorite fighting style is two-handed, with a Warrior/Mage hybrid class.
On the melee fighting styles:
Something I have noticed in the time I've played the game is that One-Handed does have some advantage over Two-Handed for a pure warrior, or at least in my experience. Dual Wielding does manage to top Two-Handed in terms of damage output, though at the expense of defense. Something that is easily remedied by investing in the Block skill.
However, I don't think that makes One-Handed a better overall choice for weapon style, and that is why I specifically mentioned pure warrior(which armor you use doesn't matter for this, but I mean "pure warrior" as a melee fighter character. Both the Warrior and Barbarian classes from previous games would count). What is problematic with making One-Handed more useful overall than Two-Handed is that it requires a lot more perks, since you have to focus on two skill trees instead of one. If you're a pure fighter, this isn't really a problem in my experience, but it does become somewhat problematic if you are playing a hybrid and have to spread your perks much thinner. Using One-Handed this way also requires a lot of micro-management, switching back and forth between a shield and off-hand weapon, which can be a liability if timed poorly.
I consider Two-Handed the better choice for hybrid characters, because it offers good damage and defense for much fewer perks. You can block with Two-Handed weapons, but that is not the primary defensive benefit for a melee fighter it has. Its longer reach is very useful when fighting enemies that wield one-handed weapons, be it dual wielding or with a shield. Especially the first 20-25 levels this is something I find useful, as Bandit Chiefs with shields are a bunch of really shield bash happy folks, with seemingly unlimited stamina.
The smaller investment of perks has its benefits as well, allowing more investment in other skills. If I, for example, is playing a Paladin character, the perks I would have used on making dual wielding more effective and my shield a wall that will keep me alive, can be available to better my healing and defensive spells, or at passive benefits like increased magicka regen(restoration tree) and magic resistance(alteration). Or, if I am more of a battlemage, getting more perks to invest in conjuration and destruction will be very useful as well.
Summation would be that One-Handed can do damage or defense better, but can't do both at the same time, and that Two-Handed can do both(though more damage leaning than defensive), but cannot do it best. The former strikes me as better if you don't have other avenues you need to spend your perks, while the later is better for hybrid characters. Of course, both weapon styles are strong enough to be usable end-game.