I've watched a lot of Palace this season and they were completely transformed when he returned. I believe a Palace fan on here also believes he could have a Mane like impact at a bigger side, so I don't think it's fair to say people who think he's good enough haven't watched him enough. He's frustrating but that's to be expected for a player of his ilk, he takes a ton of risks and is extremely direct, so it won't always come off. He also beats a man for fun and is an absolute nightmare for defenders because he's not only rapid and strong, but also extremely dangerous with the ball at his feet.
His decision making isn't the best, but has markedly improved while at Palace, and he's perfectly capable of improving even more under a top manager and learning from other top players. He has all the tools to succeed anywhere he plays imo, a manager who gives creative freedom to his players (Klopp as the best example) would get fantastic results out of him I feel. He's basically the only threat at Palace, the likes of Benteke are trash tier players so he ends up getting triple marked because the opposition is absolutely aware of how dangerous he can be. Like I said, the difference between Palace with and without him is so stark.
Personally, I'd have loved him at Spurs. The pricetag is insane but that is the reality of our current market, to Palace he's absolutely worth 60-75m because the threat of relegation would be very real if they lost him.