This is my personal tier list .. I'm a completely mediocre player, but I watch the numbers and meta around the game a lot. I have several hundred games under my belt now, and a handful of lvl 10 heroes. This list is meant to reflect heroes in the game for players down in the Bronze/Silver range (mostly Bronze), not the game in the hands of strong players.

• Top Tier - are heroes that are most winning in our MMR bracket, and additionally are essential and relatively easy to play.
• Alternates - are rather like the top tier picks, but can either be slightly weaker or harder to play.
• Sub-prime - could also have been called "well-balanced", these are heroes that are basically the norm. When played by a skilled player, they still are very potent.
• Avoids - these are heroes that are both difficult to get the most out of (compared to other heroes), and have losing win records. again, a skilled player could make a lot of impact with one of these. But if you are looking at a tier list to aid in any decision making process, these are heroes you should likely avoid.

• warrior: Johanna
• support: Uther
• specialist/dps: Nazeebo
• specialist/lane: Murky
• assassin/ranged: Jaina
• assassin/melee: Zeratul

Murky and the Lost Vikings are about the same, but TLV are very difficult for players that are not familiar with them, and constantly playing with them. Murky is fairly straight forward. On the other hand, neither Murky nor TLV are really the strongest laners.. they sit more mid-way between laning specialists and dps specialists (as opposed to, say, Azmodan or Gazlowe).

• warrior: Anub'arak, Muradin
• warrior/dps: Tyrael
• support: Rehgar
• specialist/dps: Zagara*, Sylvanas
• specialist/lane: The Lost Vikings, Gazlowe
• assassin/ranged: Kael'thas
• assassin/melee: the Butcher
• assassin/lane: Raynor

Some heroes here are difficult to get the most of: Muradin, Zagara, and the lane specialists in general are all less direct than the others.

I put Zagara as a dps specialist because in practice this is how she is played. She is a pretty fine laner too (so is Sylvanas), but people definitely tend to roll out the damage with her.

• warrior: Arthas, Diablo
• specialist/lane: Azmodan
• support: Malfurion, LiLi
• support/hybrid: Tyrande
• assassin/ranged: Nova, Valla, Falstad
• assassin/melee: Thrall
• assassin/lane: Tychus

• warrior: E.T.C., Chen, Stitches
• warrior/dps: Sonya
• support: Brightwing (unless as remedy to Stealth)
• support/hybrid: Tassadar
• specialist/lane: Abathur, Sgt. Hammer
• assassin/melee: Illidan, Kerrigan