Now I am not a professional play, nor have I scientifically analyzed all the units, but the one thing that I have noticed is that the Zerg and the Terran players slowly start to hit disadvantages later game and some core units almost become useless in the late game v Protoss. I will cite some examples and how they are almost useless unless a large number of them exist on the field. While I understand that many people will read this post and probably come up with many an example to counter my argument I do believe that for the Bronze to Gold leagues this small advantage will start to really tick people off.
The best example of this for Terran is the Siege tank. While in Starcraft 1 the original was ridiculously powerful and useful, against the late game protoss in 2 it becomes a liability. The siege tank was designed (as far as I can tell) against swarms of gateway units. Indeed most of them are relativity weak against them, but the problem that I see is that most of the units that are supposedly "bad" against it (stalkers, zealots in particular and even to a lesser degree, Colossi) they all have abilities that allow them to effectively counter-counter it. The Zealots need only have the charge ability and the stalkers blink (both of which any good protoss player already researches) and they can close the distance so fast its criminal and suddenly the siege tank that you spent over a hundred fifty minerals and one twenty five gas becomes a big tin can. Its gotten so bad that more than once I have had one lone zealot close in on my tank and kill it while they are supposedly a counter to JUST that sort of unit. The stalkers have it even easier with their blink ability meaning that they can just confidently swarm in not even caring about a siege tank where in the first game, I can personally remember even one siege tank being able to at least hold units at bay, if not kill them.
Another unit that is useless is my favorite: the battlecruiser. I LOVE terran air and I was thrilled to death about the Viking and the Banshee, but I was most excited and surprised to see the return of my favorite unit the battlecruiser. But here again I see a huge problem vs. Protoss. While I love the battlecruiser I hardly ever see it used in combat, and in fact I have made it my personal mission to use these hardy behemoths in combat once again. Now I understand being able to counter the Battlecruiser with Stalkers, but why so many counters?? The fact that you can counter them with more than one unit is OK, but in no way is having almost three that can beat it fair. Blink Stalkers almost decimate my battle cruisers as well as Void rays, but also having Archons and being able to use High Templars feedback or Storms also completely renders the Battle cruiser useless against them. I really think that the answer to this one at least, is to bring back the Redline Reactor upgrade or give them the old single powershot attack of SC1 on air targets and the bombardment against ground. My personal thought is that the cost of these units should go down at least by some. 400 minerals and 300 gas is ridiculous for a unit that can be killed by 2 void rays or one and a High Templar is pretty bad. Lower the cost down to 350 minerals and 250 gas, it would still be the most expensive unit in the game, but at least it wont be back breaking to get the funds for it. Anyway that's my rant for the Terrans
For the Zerg, I wont spend much time, not that I don't care, but that I don't play Zerg and can't do zerg players justice, but against them, they have as hard a time or even worse. The Protoss death ball is something that even pro commentators such as Husky Starcraft have said, is almost unstoppable. If its vs Terran players merely replacing the mass Colossi with some immortals renders all their mech units and Marauders almost useless, but against the Zerg simply placing more Colossi with the Thermal Lance uprgrade with a few Templars to handle the infestors or mass hydras makes for a large swarm of crispy zerg. I really think that the zerg needs a long range option, especially against the colossi, which by my watching of hundreds of replays decimate almost everything that walks in a zerg army. A dedicated long range option for the zerg needs to happen as well as some negs in the protoss deathball.
I don't want to claim that you have favoritism but with every patch and expansion it seems as though the protoss have much more to be excited about, and the terran and zerg are left confused and a little worried. Please think about it and........