Title.

sam's tier list is a good place to start, there is no 100% accuracy for 'best' champions, but it'll give you a great general idea of good picks:

http://na.leagueoflegends.com/board/....php?t=1568877

In my opinion, here are my champs that are pretty OP and almost guarantee a win (unless your teammates are feeding or the enemy team is turtling and knocking you into their fountain)

Lee Sin - is really OP since he can dash to minions/teammates if he's in trouble, or dash to minions to position for his really huge ranged Q, which also is a gap closer. His ulti is also good for positioning the enemy for death and for 1 v 1's. Any champ with high mobility is good since the map is so small and the fact that he can Q across the thick wall between mid jungle and top quite easily to initiate top ganks.

Shen - he's good since he's unkillable if you don't play stupidly. He has tanky base stats (especially magic resist), can dash through walls with his taunt, and can ulti to a teammate if necessary to escape. His taunt can also cross the thick wall in the middle - top to surprise gank or gank people hiding in the two bushes on top. His taunt is also incredible in TT since he will usually be able to get all 3 team members (as opposed to 5s where it's rare to get the whole team in one taunt) which will disrupt everything, and his ulti will prevent most ganks.

Brand - He's good since there's only 3 enemies. This means more bounces for his ult, which can do massive damage per bounce (around 300 damage, and he has 5 bounces so 1500 damage at the very least), and his single-target stun will take out 1/3 of the team as opposed to 1/5 of the team in SR. Additionally, his AOE spell will most likely be able to get all the enemy team since there's only 3 enemies.

People like Riven and Shaco and stuff are pretty OP too, but it's not necessarily a guaranteed win for you if you play them since a lot of it depends on your skill and positioning.

I wouldnt partically say any champ is "bad" on tt but some are reletively easier to play because of map size and different tactics used on tt.

Tryndamere/Sion

You can't lose

Part of TT strategy is filling roles i believe, in 5v5 you have ample room to have a comitted tank, Support, Jungler, AD and AP carries.

Characters who can fill multiple roles tend to do fairly well in TT since you essentially need to condense five roles into three characters.

Which is why you see a lot of metagolem in TT as well as damage dealing supports (like teemo/lulu/morgana) doing really well

If the enemies let you farm as Nasus, you win.

And Skarner can completely shut down all of those seemingly unkillable champions (example: all those listed above).

As far as tactics go, try AP Shaco and AP Teemo. Boxes and shrooms create insane map awareness and make your enemies fear the jungle.

thanks your message.

My personal favourite is Pantheon as of a few hours.

Ulti hits amazingly hard (not to mention the range), especially if you can get a nicely positioned one in the middle of a team battle, or simply to get some nice damage to start off an engagement with the enemy.
Excellent early game ganker as well thanks to Spear & Aegis stun.

There's a small learning curve but very fun to play if you can get some nice farm at the start.

Overall very customizable player to your own likely (with the exception that you can't really go AP).

P.S, I've found him to be able to counter/drop some AP heroes quite easily with his bursty damage.

I would recommend champ such as Nautilus (great ganks, good CC), Singed (You WILL die in the jungle to him if played right) or Lee Sin (He snowballs fairly fast and is great in general)