Has the dust cleared yet? I don't think so, at least not for me. I've barely begun to scratch the surface within LE, let alone amongst over factions.

Anyway, my tentative top three, although with the disclaimer that time will tell:

Ultroloth: A truly solid commander. Cripples titans and dragons, deals nice autodamage and holds his own when eventually based. Nice Commander Rating that will always add to morale saves. Dominate effect is cool, if rarely used. pricey, but worth it. DOn't know if he has quite that 'all in one bag' utility of Storm Silverhand, but he could.

Bat Familiar: Not the flashiest piece in the set, but could easily see enough use. He allows the use of touch spells that were rarely practical before, which is especially good when you consider that many would use the piece simply for the activation advantage. While I don't consider it the auto-include it was heralded as (but that happens every set) it has a place in many, many bands. Looks awesome too.

Large Black Dragon: Lotsa people talk trash about this piece owing to the low attack bonus, but I think that is to miss the point. If low attack bonuses could sink the piece, the Ogre Ravager couldn't have taken the Gold Champion off its perch oh-so-long-ago. And frankly, if you're not flanking with this piece you're playing it wrong.
With a breath weapon like that on a speed 10 platform, it is nigh impossible to defend against, and the battle goes down wherever they want. I would be surprised if we didn't see tri-LBD bands start to pop up in the high ranks.
The morale boost is also very nice, and brings a welcome alternative to the Wardrummer, another piece that seemed to attract the erroneous auto-include tag.

Honorable Mentions:
Wild Elf Warsinger: massive utility for 9pts, especially a damage boost, arguably the most important tech option of all. Could easily join Devis and Aramil in the 'you need a good reason not to include these guys' club.

Cormyrean War Wizard: Excellent blaster, surprisingly sturdy. Able to pump out a lot of damage quickly. Also boasts slide, one of the most powerful spells in the game. Running in pairs they can keep each other out of trouble. Great with Storm Silverhand.

Bone Naga: My own bias plays a part here. Love the faction, and have long itched for a non-commander utility spellcaster/blaster. This is it. Awkward to fit into a band, but I'm  confident it can be done.

Shield Guardian: Excellent utility piece. Adds a lot to both commanders and caster bands. Nice adaption of the Bodyguard concept.

Tiefling Warlock: Not too sure about this one yet. Love the autodamage x2. Love it, but haven't really tested it yet outside of sealed.

Dissapointments:

Strahd - offers lots, but for too much. Could've been a contender. Tsucora Quori - great concept, adds up to little on the battle field. Caller in Darkenss - same situation, except in paralyse-or-bust bands. High Inquisitor - speed kills. Van Richten - awful unless facing undead, when he's quite reasonable.

Just got back from using Vlaakith, Vampiric Dire Wolf & Thrall of Blackrazor combo with Quaggoth, Cursed Spirit, 2x Skeletal Warrior, 1x Orc Warrior. (on Drow Outpost)

The band tested well, but, I did win map initiative each time.

The Vampiric Wolf hits for 30 and heals itself (and you can funnel enemies to it). Vlaakith can first move fireball or work his way into it.

But I was really impressed with the Thrall of Blackrazor.

1 - It can exceed it's current HP.
2 - It's accurate.
3 - It can move 16 and still attack for 20 magic (once).
4 - If activation control is gained, you can make it tough for the opponent to finish off the Thrall the right way.
5 - It's fearless, so it pairs well in bands that don't require a Wardrummer or great Command rating.  (either with Werewolf Lord, Vlaakith, or Lich Necromancer)

I think it's worth moving up to 16 and spending the haste attack even if it's just to clear a tile grabber and get the bonus HP.

The Thrall and Vamp wolf are tough to kill and do damage while Vlaakith picks off fireball wounded foes.  It's really not a bad band.

The Cursed Spirit helps with Disintegrate, Stun, Morale or "a new thrall" saves.

How's that Thrall of Blackrazor look with 85hp?  How about 105?   125?