This is not a balance thing, just what units are more fun to play (okay maybe its a little balance thingy)
I play all races, but mostly Protoss and I feel like Protoss "can" be the most boring race to play.
I feel like I dont have so much different things to do.
Lets just make an example. We take the first attack unit you will get.
Zealot vs Marine vs Zergling.
Zealots early game is a very strong unit(but then also very boring)
You cant really do anything with it.
Dont get me wrong, its a really good unit (with forcefield ad guardian shield;D)
but pretty boring. The only upgrade zealot have is charge and that upgrade is not really worth going fo early. Its a good upgrade(but compared to ling speed/stim) its pretty bad. You even get it later then both ling speed and stim. It is also more expensive D:
The basic cost of a zealot is also quite high, 100minz really is much early game. I dont need to do the math for you. But 100minz is 2/3 of a gateway.
Now lets move on to the Marine.
with the power to wall off really easy marines are a really good unit early game. Both vs protoss and zerg.
If the marines did not have any abilities I guess they would be pretty boring. But they have really sick abilities and functions. They can get more hp, they can stim, they can load into bunkers, they can be healed, they are good versus many many units(like air units).
6marines in a bunker with+armor and its getting repaired. Thats a pretty good defense^^,
(lol terran upgrades XD)
The basic dps is really good(higher then stalkers lol) also they are very cheap. The fact that the unit that can drop marines also heals them works really good.
Last out for today is Zergling.
Zerglings are not as good nor as fun as Marines. But they can bee so efficient. They are not good on their own, but when you have a pack of 10-20 lings they can be really scary. Lings can be so fast both on creep and with their speed upgrade. (they run faster on mud, makes sense)
Then we have the burrow, faster attack speed and the ability to morph into banelings.
If you can get 1 zerglings to burrow on an expo. Which maybe delies an expansion for any amount of time(maybe even a terran will scan to kill it) I dont need to point that out thats really good.
The speed upgrade is almost as good as the stim upgrade for marines. Im not that good at math. But I feel like the +20% attack speed is a pretty good upgrade to. Im not good at math but doesnt increases the dps with 20%?
I really like that ability, you get it late and its expensive for being an upgrade.
I would personally like to see more low tier units get upgrades in higher tiers. (how that should work on other races I have no idea)
Like I said, this is just my personl feelings about these units. I dont think any race is imba this is just a personal comparison between units from a fun perspective.
I think its more fun to play with Zerglings and Marines then Zealots, becacuse I feel like I can do more funny stuff with them.
This post got longer then I meant. Hopefully at least someone will read all of it.
I hope you will have a great day. Peace <3