I think the Knights feel next-to-perfect now, maybe even moreso than the Hunters. I think Hunters are a little too durable (or at least don't give you enough opportunities to damage them now) on foot, but Knights feel extremely well-balanced now. Compare:
Halo 4 Knights
- Loads and loads of shields, health
- Not very obvious rank differentiation outside of "the super glowy ones will one-shot you. p.s. sometimes the ones that don't glow will too)
- Only Knight weapon with real feedback outside of instantly dying is the Light Rifle
- Virtually immune to being instakilled by headshots until a certain amount of post-shielding health is chipped off
- Couldn't be instakilled via a headshot while roaring, which felt misleading
- Minimal vehicle physics interaction / damage feedback (outside of the mantis stomp)
- Teleport ability was telegraphed alright, but the player was basically powerless to do anything about it, and the teleport more often than not just felt like a cheap way for knights to eject from encounters as opposed to Engineers healing enemies, Elites running for cover, etc.
Halo 5 Knights
- Very clear weak spots, all of which present themselves in a progressive fashion
- Player is presented with multiple opportunities to one-shot Knights
- Shooting the exposed skull will result in an instant kill
- Physics-wise, Knights feel less "building with legs" and more "lumbering washing machine that can take a hit, rather than being an insurmountable monolith
- Very blatant audio cues to warn you of different stages of Knight engagement (roaring, "BUH HUH HUHHHHH" when you've been spotted, etc)
- Very clear rank differentiation as well as weapon feedback - you can quickly glean whether the Knight is carrying an Incineration Cannon, Scattershot, etc.
- Knight ranks / weapons make them feel like they actually serve important, separate roles, rather than "universal lumbering instakill machine"
- Higher-ranking Knights (esp. Battlewagons with Incineration Cannons) feel very traditional Hunter-esque in that they're less "bullet sponge infantry" and more "mobile weapons platform"
- Knights that fire Incineration Cannon mortars feel very CE Wraith-esque, but more vulnerable
- Knight weakpoints feel CE Hunter-ish except more intentional, namely being able to shred them in seconds using the Needler (or even quickly with Hailstorm)
I think the Soldiers will probably see a similar level of improvement come Halo 6.