I think Kennen could really use some help. With the fights being so fast paced, he runs out of energy much too quickly. Kennen cannot put out decent damage, or get 3 Marks of the Storm for his stun, if he is not able to use his abilities a bit more.

Not being able to itemize for CDR puts Kennen and some other energy based champs at a large disadvantage, imo. Many other mana-based champs are itemizing for it, and they are able to spam their abilities much faster as a result. Meanwhile, Kennen runs out of energy after 3 abilities, and then what?

I would love to be able to just itemize for some energy, but there aren't any such items.

Fury decay/generation rate needs to be looked at, but there's more issues with the champions than just fury. I don't think it'll make Trynd/Renekton that great even if fury didn't decay at all.

Renekton and Trynd have fury decay, which makes it really hard for them to do well on Dominion.

I think Shyvana's irrelevance in Dominion is based far more on her skillset than her resource. Not much point in a bruiser without CC.

I can't comment on Akali, or Kennen as I neither play as or against them often enough.

Zed is just silly weak, especially at my ELO. Other assassains have higher burst with better poke and pushing power and better survivability in team fights (although they might not have his theoretically long range). The fact that he's limited by energy certainly doesn't help.

Lee Sin is fine. He has enough energy recovery mechanics that with smart play he continuously contribute at all stages of the game.

Shen needs help, specifically in the energy department. You need your abilities to contribute meaningfully to fights, but they spend more time off cd but with insufficient energy to cast than they do on cd. I mean he barely has enough max energy to give one full rotation of his skills, and a missed taunt is a complete and immedate death sentence.

They've nerfed Tryndemere since I played him, but he did okay if he's tanky/ignored enough to build up rage without being killed. When I play him (which is not often b/c I'm bad at melee carry), I run a high crit chance rune page (9 yellows and 2 reds), which lets you build up rage quickly enough if you live long enough. I think he might be solvable with some good tank/crit items (atmas doesn't work), but again, I'm working with impressions coming from an old patch.

Renekton works out being suboptimal, but still playable (assuming your good with his mechanics) because he isn't as reliant on range for decent AA damage and survivability as Trynd; but I play him more as a tank/bruiser than pure bruiser (if that makes sense).

I felt Shyvana did alright (suboptimal, but playable), especially in the rage department. She's not super reliant on her ult, and scales so well with attack speed that she can function as she is. Her real problem is she doesn't have any way to turn her strong farming power into a meaningful advantage because how vulnerable she is to being simultaneously harassed out of lane and outpushed by any decent AoE bot laner.

tl;dr Shen needs serious help, Tryndamere, Renekton, Shyvana need small buffs to be competitive and Lee Sin is fine.