So I've been playing HotS for a while now and I'm coming to the conclusion that the game needs more and more obvious power spikes.
Heroes like Azmodan, Stitches, Raynor, Artanis, Tyrande, Falstad get power very incrementally with their quest talents (seasoned marksman etc) and perform solidly if not remarkably throughout the early-mid game and then exceptionally well in the late and very late game. On the flipside, heroes with power spikes would work well at certain points during the early-mid-late game and then not as well in the very late game. Such heroes at the present I guess would be Kael'thas at 13, Nova at 7, ETC at 10. KT gets his chain bomb thing which everyone seems to hate, Nova gets a significant damage boost from a combo and ETC gets a large aoe stun with a long duration.
I argue that power spike mechanics are more fun than incremental boosts, giving one side a timed advantage that they should use until the opposing team gets to where they spike and the roles of attacker vs defender are reversed. With the addition of Greymane as the newest hero this looks like the trend, even Lunara I guess is a spike hero at 16 with that basic attack range increase even if she is weaksauce.
Actually that brings me onto another point. Heroes like Nazeebo and Lunara that always top the damage charts are way more useless than it appears. Almost all damage that doesn't lead to a kill or retreat (with the loss of lane xp anyway) is wasted. The type of damage that these two champs at least do is so slow due to how poisons work in the game that, although they are doing continuous damage over the entire game and yes they will actually get the kills sometimes due to an actual burst character getting them so low that a single poison tick finishes them, the damage they do does not reflect how powerful they are.
Instead compare with an assassin like Illidan (I would include Butcher if he wasn't so bad) who almost never tops the damage charts but usually ends up with more kills and more 'useful' damage done. Illidan can run down fleeing enemy heroes to secure xp from the kill and has burst damage enough to take out almost all assassins with ease. What I'm saying is damage charts (and healing, tanking, kills, assists stats) aren't reflective of usefulness and players who quote them in an attempt to prove their worth on a team plainly don't understand how the game and strategy in general works.