I would recommend Irelia. Cho'gath doesn't do quite as well against ranged top laners who can kite him and a lot of people have percent health damage top at the moment. Irelia, on the other hand, is good at laning against ranged opponents and can duel or assassinate most champions top lane. The ranged champions are squishy enough for her to easily kill and a lot of the tanks don't do well against her sustain and mixed damage.
Cho'gath is a good top laner with a lot of sustain, CC, and harassment. I used to play him a quite a bit and still play him occasionally.
Typically, you max W against ranged opponents and E against melee opponents. My typical core items were Frozen Heart, Spirit Visage, and Randuin's Omen to get durability and CDR. Afterwards, I would usually get Thornmail and either Wit's End or Banshee's Veil (though I would occasionally purchase Zephyr for the CDR, MS, Attack Speed, and Tenacity because I though it was good).
Generally, you can sustain through most poke after a few levels and, if you maxed E against melee opponents, outtrade them very well. When trading, I would recommend forcing short trades frequently against your opponents and backing off to sustain up. When you have your opponent low enough, you can just ult them for a kill or to force them out of lane.
Edit: Oh cool, didn't know that using a bunch of hyphens on their own line would give me a line break.