Personally haven't played any ranked as I've been more of an off-and-on player until recently (as well as my distaste for things like solo/duo queue), but I've certainly played enough to have confidence in my play with multiple solo top champs, though not all of them will make this list.
In my opinion (and no particular order):
- Shen - He's Shen. He's a flippin' ninja. Not to mention decent farming ability between Ki Strike and his Q, as well as built-in sustain and a global ultimate that allows him to split push like a boss or turn the tides of a teamfight across the map. I generally build him with a bit of burst, getting Wit's End and a Tri Force on top of Merc Treads, Sunfire Cape, Randuin's Omen, and generally a Force of Nature. (Heart of Gold and Kage's Lucky Pick early until you need the slots, obv for gold/10 and Pick helps Shen last-hit with Q early-mid game.) This allows you to take the brunt of the enemy team's damage with little issue between his taunt and shield, and the attack speed gives you enough burst from Ki Strike to drop enemy carries in under 10 seconds as well as increased sustain from your Q. I've had a lot of success as Shen laning against anyone that needs to melee to farm, as initiating with taunt makes Shen very difficult to 1v1.
- Riven - Riven is an adc disguised as a melee bruiser. My biggest issue with her would have to be the fact that she inherently pushes the lane by fighting and closing, as her lack of a ranged harass is mostly made up for by her mobility. She can be countered hard, but if played well she can farm on par with most carries in the game, while harassing hard and avoiding damage with her mobility. She's a beast early game, especially once she hits 3, but she doesn't fall off late-game... She scales just as hard. She can be built as an off-tank, but I would recommend building her as more of a tanky adc. My default build, assuming no one on the other team is abnormally fed, is: Early Wriggle's, finishing boots into Merc Treads after and going straight for a Phage before rushing my first BT. Then I'll generally finish my Mallet, before starting my Last Whisper or Ghostblade (depending on the amount of armor stacking going on), and then going straight for GA. Then sell wriggle's for my second BT or finish my LW/GB, depending. Sometimes go for GA earlier if I'm being focused hard in teamfights.
- Trundle - Yeah, Trundle. I almost never play him top, but considering he's a hard counter to Jax and a decent counter to Yorick - 2 champs that are very difficult to counter - it's good to be able to pull him out when you need to, and he's also extremely good at ganking other lanes and pursuing in teamfights. Trundle is underrated IMO, mostly because he doesn't farm exceptionally well, but he counters the vast majority of AD top champs. I build him as an off-tank, as he tends to just wear people down in chunks when fighting as opposed to stomping their face in 4 seconds flat. Try to get your Q off whenever you can on the nearest AD champ, preferably the one attacking you, and try to use your E to shutup escape routes and force fights on your W, where your movement and attack speed are significantly increased.
- AD Kennen - Ahh yes, AD Kennen. Scoff if you will, but he's probably one of the most underrated champ builds out there. Yes, he's squishy if CC'd. But his farm and harass are very nearly unstoppable, and even as AD about 20-30% of your damage (mostly your burst) will be magic dmg, making him very difficult to counter with gear. On top of that add his stunlock capability in teamfights and insane mobility, Kennen is an perfectly viable pick to counter a bruiser top. (I've had some trouble with Panth and Jax because of their ability to close immediately, but been very successful counters champs like Riven, Darius, Olaf, Nasus, etc.) Build him as an ADC, as he's already more mobile and thus more self-sufficient than most adcs (Kog'Maw, anyone?) so a GA is usually enough to keep me alive as long as my team is decent as peeling. I generally build Berserker's Greaves, Infinity Edge, Tri Force, PD, BT and a GA, not in that order necessarily. Sometimes get a early-mid game Quicksilver Sash if laning against an AP like Diana or Akali.
- Jax - He's Jax. Counters a lot of champs that stomp most people 1v1 (Riven, Darius, Olaf, Teemo, etc) and farms/scales hard into late game. He's mobile, he's bursty, inherently tanky without much need to build for it, and oh yeah he can jump into your team, stun you all and kill your adc in 5 seconds or less. I've seen a number of different builds, but I go mainly for attack speed and a mix of ad/ap, with a bit of tankiness. His ult and counter strike make him hard to take down, even if you aren't built for tanking. His main weakness I would say is no sustain unless you build for it, though it's not very hard to do so.
- Jayce - Personally I don't see Jayce as "OP" but he's certainly a strong choice for top. His ability to switch between ranged and melee and put out good damage via both is insane, and he can help the entire team move around the map faster, allowing for more aggressive early-game invasions as well as help with pursuing or eluding enemies. That being said, I have barely played Jayce at all and can't provide much more insight into the champ than that.
- Singed - Trololol. Singed wants you to try to 1v1 him. He wants to sling you into his minions and wear you down while farming the **** out of your lane and keeping you pinned against your turret. That, along with the fact that he's a mobile, relatively high cc tank (no stuns though, meh) with an underestimated dmg capability late game... That should be enough to tell you Singed is a boss. Not only that, but having a legitimate tank holding his own solo top allows for much more creative picks across the board for your team, especially your jungler. Singed is that guy that's overly aggressive and there's nothing you can do about it. Against Singed, unless you get fed out of lane or something, you're generally reduced to a farmfest, hoping you just outscale him late game.
- Vladimir - If you're running a double AP comp and need a high-burst, high-sustain fighter/carry, Vlad is your guy. His farm is pretty difficult to stop as his Q does dmg instantly, and his dive and life drain from his Q make him pretty difficult to push out of lane. I rarely play AP top, but Vlad is a solid choice, especially against champs that need to melee to farm and leave themselves open to his harass, which can be brutal. Build him as a bit of a tanky AP carry, focusing on AP>health because of his passive (bonus health based on AP, as well as the inverse, not stacking on itself) - Rod of Ages, Rylai's, etc.
- Diana/Akali - I put these two together because they're obviously very similar, both AP assassins capable of laning mid or top. Diana is the tankier version, though Akali perhaps has more utility in her stealth. Both are very strong at farming, harassing, and closing. If I had to choose between the two I would probably pick Diana, simply because I enjoy playing a more bruising type of champ, but she's also a very powerful assassin. I've played very little Akali but several players I know hold her in the same light as Diana.
- Malphite - There's a reason Malph gets banned constantly. He's absurdly tanky against ADs, farms fairly well for his tankiness, and his ult and slow are pretty silly. I haven't gone out of my way to play him because of his tendency to get the **** banned out of him, but I know at least 4 or 5 solo top players that swear by him. His ganks out of the jungle are also very scary, like Trundle.
*NOTE* - I have never been inclined in the least bit to play Olaf, Teemo, or Darius. I've despised these champs since they were released, and so none of them made it on to my list. But that's just me, please share/discuss your own opinions or ideas!