Brave shipped a descent product. There's plenty of "ICOs" that contributed to open source protocols or standards on Ethereum, but yeah, it's the minority. I don't think most companies during the dot com com contributed anything either, nor will all these AI startups raising absurd amounts of money for hallucinating your next road trip.
I do not know which one was/is the most successful.
In terms of real-world use cases - I am familiar with and excited about WindingTree. https://windingtree.com/
They are building a platform to make the distribution of travel products (hotel rooms, flights and more) - arguably digital tokens with real-world value - more inclusive.
They did an ICO with a token called LIF that I bought at that time (not to dump later, but because I could identify with the problem and wanted to support them)
Ethereum is probably the most successful ICO. Out of the ICO's which have launched much like startups less than 10% survive and yes many were also scams. Some examples of succesful ones though are MakerDAO and Synthetix. Both have successful running products which generate large amounts of fees.
It is more common now for a project to distribute tokens after it has a running product to incentivise early users and integraters. ICO's still happen but are oftne restricted to venture capitalists and registered investors.
I would love to hear from a crypto fan, which was the most successful ICO? And where is it today?