Urgot falls off because of how you and most other players build him, if you really look at his kit... and I mean really take a look at what its for..
hes meant as an ADC BRUISER... yes yes... it sounds weird I know... but urgots whole style is about getting into a fight, and constantly hitting EVERYONE with your auto attacks in the fights, mainly the hard AP or AD carrys to reduce their damage.
Items like Manamune are obvious, but frozen heart, frozen mallet, randuins, banshees, last whisper should almost 99% of the time make up the rest of your kit.
WITH THAT ASSIDE
other very viable top laners who can zone people hard
Jarvan - If you use his passive properly, no melee, and half of the ranged tops cant out trade you in lane, simply hit them, then go back to farming, when the 8-9 second delay falls off, hit them again, keep doing this.
Jayce - a good jayce can hard zone most champions, and he has good self peels along with good long range burst, he can really match up against most people. When stuck vs a quin, just wait till her Q falls off by backing off, then go back in, you can easily out trade her
Lee - Often overlooked because hes a jungler, his laning can be amazing if you know how to properly play him ( this means not always maxing Q first against some enemys, sometimes you want the higher shield )
Renekton - get in, hit a Q to restore HP, hit a stun, dive back away. He can harass even ranged champions with little counter from enemys outside people with blinds
VI - Another champion capable of sitting behind a wave and still poking enemys, then closing gaps hard and fast for ganks
Yorick - He falls off late game only if you build him improperly, just like urgot, the choices you make in gear will determine how effective or how terrible you do
Wukong - he doesn't fall off... simply put, if you learn how to use your S key to "fake" stealth juke, and play right, you will almost never get beat