Decentralized exchanges (e.g. uniswap) - users provide all the liquidity, get all the profit, has guarantees etc. Currently eth has high fees (this wasnt the case until recently and wont be in the future with layer 2) so it might look less great but it already has huge traction especially for smaller coins who you'd otherwise have to trade through tiny exchanges that are harder to trust.

Similar for non-currency exchanges (like synthetix) which provide a comparable ways to trade near-arbitrary assets, though admittedly that is less proven to be a clear winner so far.