From a 1v1 "how much do I want to make this unit?" perspective:
S tier (this frequently wins games)
Grizzly can define the course of a battle and it's power to push and attrit skirms is amazing. Killing a skirm every few seconds it will generally make cost in under a minute while being hard to kill as long as there's a small escort.
A tier (sometimes game winning)
Another game defining superskirm, however the fact you'll probably be using it on spider maps where widows lurk makes it a lot dicier than Grizzly in practice (whose hp makes a single widow an unreliable counter).
A few Thugs can make Rogues and Felons much more survivable and the combined blob's porcbusting power is unmatched.
The good range, insta-hit and stun make it a pretty flexible unit applicable in a range of situations. Most notably against tank where it essentially counters the entire factory (technically a Cyclops can kite a knight ball indefinitely, but in practice with retreat zones they won't actually die and you probably have area cloaking by then).
High speed, high hp and decent DPS. The most assaulty of all the assaults is surprisingly effective as monospam, able to sweep across big open maps in an unstoppable way to threaten important things from a range of angles.
B tier (situational but important)
While Halberd's on-paper stats are amazing it lacks the flexibility and battle power of ravager and doesn't solve many problems Hover has (other than LoS for Lance which a Sparrow can often provide). While a Ravager can go an kill some light porc and return home safely, a Halberd will often die due to its need to unarmor.
S tier vs Jumpfac (can be monospammed!), other than that there's rarely a good use for it as Redbacks or Recluse can handle porc.
High HP and jump lets it dive porc and coms to great effect. It's quite specialized though.
Not really very assaulty, but its ability to go in, kill that com and get out is valuable.
That said, gunship starts and switches are things I rarely do, so hard to rate.
More a riot than anything else, but a blob of hp that big means it can serve as an assault in a pinch and it's a good riot and tank.
Very strong against hover, with high speed, ok hp and high damage. Needs a bit of fiddling to ensure both guns hit well. It can take on porc quite effectively.
C tier (eh)
Sort of just there, you build it to raid and retreat, particularly against porc, but it doesn't really have many strong matchups and its effective DPS per cost is very low (partly due to its slow bullet speed making chasing/hitting difficult and partly because its anti-breakpoint damage: 8 seconds per Lotus is painful).
It can dive a Lance if your opponent is inattentive and thus doesn't use the fact that Minotaur is only 24 elmo faster than a Lance.
D tier (you probably don't want to build this)
The poor man's Grizzly: a heavy skirm. Given its price, there are very few situations where you want to build this rather than fac switch to fix the holes in tank's gameplan (maybe if your enemy is spamming Minotaurs or has built a Dante to kill your Minotaurs).
The only way this will work as a surprise strider is if neither of you have gone air much in a fairly high metal game (probably dense and small). In practice there was almost certainly something more important you should have made, like a Silo.
E tier (you should never build this)
There is never a reason to make this in 1v1.