So are you asking about the strongest early game champions? I sort of tailored my list to strong laners anyways, but, I mean, you can, with more ease than most champions, get a lvl 1 first blood in 1v1 with Riven and Yasuo, especially in mid lane where champions are typically squishier and need a few levels to get their spells.
As far as what Riot would consider a good bar, (and I'm still surprised about Renekton top, since he dominates most lanes, seems a little unhealthy):
Top: Renekton (I guess? I would still say Shyvana since I think it's been longer since we've seen a Shyvana nerf than Renekton nerf, but idk)
Jungle: Pantheon - Basically out-duals everyone early. Also he hasn't really been touched as far as nerfs go, (minor changes to his ult that most people didn't even know about, they were more bug-fixes than nerfs imo).
Mid: Orianna - Consistently a strong laner, has been picked in competitive play for a long time, and I can't recall the last Orianna nerf I saw.
ADC: Caitlyn - Same as Orianna, also because Lucian just got a minor nerf and may be looking at a few more in the future.
Support: Thresh - Same as above. I don't think Thresh has been changed too much recently (I think there have been some minor issues, but nothing that screams that the champion is too unbalanced).