You are comparing the Uruk-Hai to humans or elves, which isn't a very relevant comparison. Instead, compare them to the other breeds of orcs that serve Sauron, which the Uruk-Hai were bred as a replacement for.
Here is a confrontation between the Uruk-Hai and some northern Orcs. Uglúk is the Uruk-Hai, Grishnákh is the northern Orc. Emphases are mine. (Book III, Chapter 3: The Uruk-Hai)
In the twilight he saw a large black Orc, probably Uglúk, standing facing Grishnákh, a short crook-legged creature, very broad and with long arms that hung almost to the ground. Round them were many smaller goblins. Pippin supposed that these were the ones from the North. They had drawn their knives and swords, but hesitated to attack Uglúk.
Uglúk shouted, and a number of other Orcs of nearly his own size ran up. Then suddenly, without warning, Uglúk sprang forwards, and with two swift strokes swept the heads off two of his opponents.
We can see that the Uruk-Hai are bigger, stronger and more intimidating then the other orcs, and can kill them brutally and with barely a thought. Grishnákh is a mean and devious orc, but he knows he can't beat them in a fight.
The Uruk-Hai are also braver than the regular orcs, who are prone to panic and desert when the going gets tough. Again, this is Ugluk talking to the northen Orcs, later in the same chapter:
'Let the fighting Uruk-hai do the work, as usual. If you're afraid of the Whiteskins, run! Run! There's the forest,' he shouted, pointing ahead.
And they are implacable, and do not fear the sun: (Book III, Chapter 7: Helm's Deep)
'What of the dawn?' they jeered. 'We are the Uruk-hai: we do not stop the fight for night or day, for fair weather or for storm. We come to kill, by sun or moon. What of the dawn?'
whereas regular orcs do (Book IV, Chapter 4: Of Herbs and Stewed Rbbits)
but though Orcs may shun the sunlight. there were too many places here where they could lie hid and watch;
All in all, most of Sauron's orc armies are, individually, no match for an equivalent human force. They are smaller, weaker, less disciplined and cowardly, and make up for it in sheer numbers alone. The Uruk-Hai were bred to be as vicious and numerous as orcs, but as large and dangerous as humans, or at least closer to that than the average orc.