The reason Blaise defines the game is because he breaks so many rules in ways that no other model does, in a way that cannot be mitigated except by another Blaise. Command cards are an essential part of the game, and not knowing the exact hand your opponent has is an essential part of the game. Blaise mitigates every part of command cards. He prevents you from having them, he negates the benefit of holding onto them, and he punishes using them. He removes a huge element of the game, but only for that player. The opponent still has to play the command card guessing game, knowing that even if he plays perfectly around what command cards his opponent might have, he can never win that aspect.
And ignoring everything else, Agent Blaise is cool and fun to play. Interesting abilities and introducing a new archetype for Imperials. I understand what FFG wanted from Blaise. But (I believe) Blaise is FFG's biggest misstep in Imperial Assault.
General Sorin is the Imperial leader for mechanical warfare. He himself is nothing impressive, with a weak attack with abnormally good surges and a mediocre health pool. He will rarely attack himself, using his Bombardment ability to give an attack to another friendly figure, which gains Blast 1. But the entire reason to bring Sorin lies in his Advanced Firepower rule, which gives all adjacent Droids and Vehicles surges for damage, stun, and focus. Handing out these surges can make a huge impact, potentially giving Probes or HKs perpetual focus or a stun on demand. Sorin is not a figure you add to a list, he's a figure you build a list around. And with Advanced Comms Systems, an upgrade that changes adjacent to be within three spaces, he's entirely feasible to build a good list with. (Hint: Look at the traits of the upcoming Jet Troopers from Jabba's Palace)
Thoughts on Unit Options
Imperials have the best generic Troopers. Stormtroopers and Heavy Stormtroopers are great. Imperials also have the best centerpiece models. Vader, RCG, Sorin, and Kayn all are worth building an entire list around. Their support is lacking many of the options the other factions have (notably Rebels with Gideon and C-3PO), but with the usefulness of the Imperial Officer and the meta-knowledge of Blaise, Imperials don't much feel the lack.
There are very few bad Imperial options, but the general strength of some of the options make choosing even good models less than competitive.
Combatting the Meta
The current meta is that of elite Troopers, with good health and damage output, though typically lower numbers. Often backed by support options, be it Blaise with his command card shenanigans or Gideon+C-3PO for focus.
Imperials are the meta. Having the best generic Troopers makes a strong list. There's no shortage of Trooper lists running only on generics. Application of other choices like Blaise, Probe Droids, etc. make an endless search for your favorite combination. But Trooper is far from the only good Imperial list. I think any centerpiece list is a viable contender as well.
I've got this crack theory that Vader or RCG is the way to go when trying to counter the meta. Both are nigh-impervious to even elite Troopers. Vader is somewhat miffed by the loss of his command cards, but is a murder machine even without them. RCG doesn't at all care about command cards, he's largely not even going to use them barring the occasional supersonic Urgency or a cheeky Flurry of Blades.
I see Imperials as a solid roster of generic units, either by themselves of focused around one specific leader model. There's nearly no wrong choice when it comes to making an Imperial list.
But that's my thoughts. What are yours? Any conflicting opinions or questions left for me would be greatly appreciated.