LeBlanc is oppressive.
She is way too oppressive in lane, and definitely is deserving of nerfs. Even if she doesn't get any nerfs at all, she is sitting at a 50% ban rate, and is banned more frequently than 120+ champions in the roster right now. The fact her winrate is as high as it is, on one of the most difficult to play champions, this early after the rework, means that she is not in a healthy state. If anything, her winrate will only increase as people get better with her and play around her strengths.
If enemy plays safe and backs off the wave, they lose CS and are easy to chain. If enemy tries for a push & roam strategy, LB can push harder and roam better. If enemy tries to play anywhere near the wave to avoid getting chained, they will get tagged by W and will get zoned until sigil wears off, or risk getting a Q bounce. If enemy tries to play safe and farm, she can jump over the wave and nuke them down.
Before, LB's weakness was twofold - she would have to spend mana on waveclearing if the enemy decided to push, OR if they stayed back out of W range, LB would have to waste a lot of mana for a W (no damage) -> Q -> E, with E and Q costing double the mana that they do now. When I play LB it doesn't matter how safe the enemy plays, how tanky they build, or how much they farm. Unless their name is Ryze, there is almost nothing anyone can do in lane vs LB right now.
She always has the option to just sit and farm if she doesn't feel like fighting. The only bad lane matchup she has right now is Ryze. She currently has the highest% winrate for mid lane in higher tiers of play. She is disgusting and is very deserving of nerfs. I don't like the rework either, but there is absolutely no question she is stronger than she was, by a lot. She has way too many options early game to get very fed and put everyone else behind. If you look at winrate% over game length, it is starting to even itself out, and even when the game is past 35 minutes, she still retains a higher winrate than a lot of other mids, compared to a steep skislope that it was during the first two weeks of the rework's release.
The only way for her to get off her 50% ban rate would be either for her to receive pretty drastic nerfs to every part of her kit (damage, mana costs, chain length, sigil duration, W speed), or literally buff every single other champion to have the same utility/dmg that she has. I would wholeheartedly support nerfs just to get my champion back. I know this champion is a lot of people's baby, but I'd rather have a weak champion that is actually playable in ranked, vs a champion that I never get to play because everyone bans her every single game.