Hi there, this is Qu4rk, captain for Comunidad Genesis Heroes of the Storm squad. After getting selected in the early stages of the Alpha test, I have been spending uncountable hours in the Nexus, playing mostly Tanky/Bruiser heroes (1300+ games and increasing!). I've hit rank 1 after a couple weeks of ranked play on EU and have around 3.8k MMR (hotslogs). Today I'm looking forward to share my insights about Sonya and hopefuly starting some discussion about them. All constructive criticism is widely welcome!
p.s: Since this is my first guide ever, I apologize in advance for the newbie mistakes I will for sure make.

EDIT: I am overwhelmed! 10k+ visits and a nice score :D Thanks everyone, keep it up!
EDIT 2: Well, Sonya has been hit (twice) by the nerf hammer. First, 20% reduction on the talent giving Seismic Slam insane damage and, second, a (in my honest opinion, not needed nerf on a champion struggling to find a spot in the current meta) +20s cooldown on Leap. Not cool, Blizzard!
Also thanks for the 20k+ visits and the votes! :>
EDIT 3: added some changes due to new patches.
EDIT 4: Added changes due to 10/Feb/15 patch. Also 80k+ views, amazing!!!

Sonya, the female Barbarian from the Diablo franchise, is a strong melee tank/bruiser hero, designed to jump right into the heart of the enemy team and unleash hell.

Pros
- One of the best initiators in the game.
- A mix of burst damage and bulkyness.
- Strong duelist.
- Fair jungler.

Cons
- Heavily reliant on the team to capitalize on her initiations.
- Achieves spike damage by sacrificing tanky talents.
- More vulnerable to CC than almost every other tank (unlike many others, she doesn't have Relentless).

Trait: Fury - Sonya builds fury by dealing or taking damage (classic warrior-class resource mechanic). Using an ability grants Sonya 10% movement speed for 4 seconds. This passive is useful and kind of compensates for Sonya's weakness regarding snares. If she's not snared, Sonya becomes a killing machine spamming Seismic Slams at your back and pursuing you even into the deepest circles of Hell.

Q: Ancient Spear - Throws a spear towards the first enemy hit, dealing a moderate amount of damage and briefly stunning him while you get pulled into the target. If it hits, generates 20 UPDATE 40 Fury. One of your initiating tools (the only one pre-10), with a 13s cooldown. Not much to comment, generates Fury which is cool. Post-10 try to initiate with into teamfights and save this to decimate the fleeing targets.

W: Seismic Slam - Deals a ****load of damage to the target and a decent amount to enemies in a cone behind it. This is your primary damage source, which you are going to make sure you improve with talents. It has a 1s cooldown, which means that while you have enough Fury you will be spamming it and smashing faces.

E: Whirlwind - Deals a fair amount of damage to enemies over 4 seconds, and heals you for 30% of the damage dealt. Before the last patch, this skill was spammable while you had enough fury to pay for it and was an amazing asset for Sonya in the mercenary camps with almost infinite sustain. Now, with its 10s cooldown just makes the camps a bit easier to hold but nothing compared with the superiority it offered pre-patch.

R: Leap - Leap into the target location, dealing enemies a low amount of damage and stunning them for 1.5s. The Heroic ability we are going for 99.9% of the time, which makes Sonya the powerful initiator she is and should make you tremble in fear when you meet one in the battlefield. If a Sonya happens to catch your team together, you will probably be decimated in no time. This initiation is a double eged blade, though. For this to become an effective threat, there MUST be a follow up by the team. Otherwise, you will find yourself among 5 enemies and get obliterated in (almost) no time. So be careful, this skill can make you win or throw a game.

R: Wrath of the Berserker - Gain +40% Bonus Damage to all Basic Attacks and Abilities. Disables against you have 50% reduced duration. With the recent 10% damage buff, this may become a viable pick and shift Sonya's playstyle from and initiator to a dps-style warrior who follows in.

Level 1
Unless you are looking to undertake the role of mega tank (I would suggest you to choose another warrior in that case), you are going to be spending a ton of fury for those sexy Seismic Slam. So, Shot of Fury is basically 25 free fury every 45s. Go for it. UPDATE buffed from 25 fury per activation to 50. Even more worth now.
Level 4
Furious Blow is the bread and butter of your talent build. Increased Seismic Slam damage at a the cost of a bit more fury. So worth it.UPDATE Got nerfed from 50% damage to 30%. That made Sonya one of the most unplayed characters on the game. With the recent buff (up to 40% extra damage), she will start gainig back some of her power.
Level 7
Alongside with the previous talent, we find another valuable asset to our damage: Shattered Ground. It basically turns all the cone damage for Seismic Slam in hell on earth. Must have.
Level 10
Impressions about heroic abilities have already been stated.UPDATE Before, I would always go for Leap but with the recent buff on Wrath of the Berserker I would go for either heroic ability depending on the team around you. Lacking initiation? Leap time. You need follow on engages? Unleash Wrath of the Berserker.
Level 13
Ok, so we've got the damages. At this point of the game teamfights will be mostly erupting every now and then (if they hadn't still), and an important thing to keep in mind is that we can't bash enemies if we are dead. So, picking Spell Shield ensures we will be soaking some damage when we engage the teamfights, since we aren't gonna be ignored beign the nearest enemy.
Level 16
While on our quest for some survivability, Stoneskin appears as an unvaluable addition for our kit. With the huge HP pool of Sonya, this talent shines even brighter than on a squishier hero. Instapick!
Level 20
RIP Resurgence of the Storm. This leaves as the only suitable talent the upgrade of your Heroic Ability.
UPDATEThe two new talents may be really ineteresting additions, also for very specific scenarios. I would pick them situationally depending on how the game has evolved until the moment you hit 20. Don't be afraid to experiment with these new options!UPDATE After a bit testing, Hardened Shield has definately won me over. Jump and tank, *****es!

Early game

Strategies vary in each map, but with Sonya we will mostly try to give our team map pressure by controlling the mercenary camps and making those mercenaries fight for our team.
Specific strategies for other maps include lane presence near an altar at Dragon Shire and (optional) beign the doubloon carrier in Blackheart's Bay.

Mid game

Around mid game we have already picked all our damage boosters, and this is where Sonya really shines. Teamfights will start to be more frequent at this point of the game and, although you still lack some survivability, you initiation and damage will mostly wreck the enemy team. Abuse this phase.

Late game

At this point of the game, our role in the team will vary a little. We will still be engaging, but our carries will have achieved their peak on damage (enemy's team also!), so our main goal should be somehow balanced between providing a solid frontline for our carries and trying to reach enemy's team carries (if we can't kill them, just them having to relocate and go backwards makes them lose DPS, which is worth.)

So, that's it! I would like to emphasize that I don't believe this is the only way to play and build Sonya, or that other talents aren't viable. I would really like to hear your opinions!
If you are looking for a solid, fun hero to play (and not very expensive), give her a try :D
Also, since I'm a newbie guide maker, I would like to give credit to Glaurung's "Make your enemies NEED Stitches" and Sneakybeavr's "(Team Curse) Crs Sneaky - Support Rehgar" guides, which are awesome and I used to inspire myself and find a way to organize things I wanted to say and how to put them. Btw, check'em out!
Thanks for your time if you have made it to this point, you're awesome <3

Qu4rk