Ling: + speed
Roach: +speed
Baneling: +speed
Hydra: +1 range
Ultra: +2 armor
The move burrow roach is something more interesting.
Terran upgrades feel more different, you really upgrade an unit to something else.
stim pack
concussive shell
cloak
250mm canon
yamato canon
siege tank
pre igniter
And the funny thing is that the most controversed terran unit is the one with a speed upgrade namely the reaper.
Toss is half boring, half funny:
chargelot is a speed upgrade but more dynamic with his pros and cons
blink
+3 range on colossi feels more interesting strategicly than a +1
But for otehr units you have the same awful zerg pattern:
warp prism: +speed
void rays: +speed
observer: +speed
Boring upgrades = less gameplay/strats.