Always make sure these heroes are banned if it's likely that they will be picked.
Best in Role
Best heroes to pick if you want to climb HL
Tyrande better blind pick than Deckard.
Sgt.Hammer good into Raynor, Fenix. Mediocre into Hanzo
Yrel for lane priorty. Blaze for teamfights
Tyrael E 7 enables meta rdps, support styled tank that should play for his backline. Sanc to prevent enemy initial engage onto backline.
Strong secondary options
Malfurion good into tyrande.
Jaina good with deckard, counters Raynor, weak vs Hammer Hanzo Fenix.
Tracer good into Hanzo, bad into Fenix, Hammer, Raynor.
Li-ming not good as a primary dps.
Thrall, Zeratul, Kerrigan good in triple melee.
Don't go Haymaker Muradin, it creates a forced play-style increasing margin of error in teamfights.
Always go Seven-sided strike for Kharazim.
Brightwing good to pick vs playmakers (Tracer, Zeratul, Dehaka)
Arthas better on maps without important solo lane (BOE, Tomb, Infernal, Alterac, Volskaya).
Difficult to win with, yet high pick rates
Ana is my least favorite popular support pick in Hero league. She is mechanically difficult to pull off unless you are supporting a Sgt.Hammer.
Azmodan and Junkrat make teamfights very hard to win and only have slight macro benefits.
Samuro creates frontline issues in teamfights and makes it hard for your ranged dps to trade into enemies.
Falstad Z got nerfed and is weak in teamfights.
Zuljin is too health and mana inefficient with a very weak early-mid game.