Privacy.

Tor is an overglorified government VPN. where a path from your computer is created through a few nodes and data flows on both sides.

This means that having a few nodes monitored gives good access to what you are doing through browser fingerprinting and other techniques.

I2P breaks the data into multiple pieces and each follows a different random path, which then gets changed again. The return path is not the same either, also changes.

So the effort of monitoring I2P is exponentially higher and exponentially more difficult to assemble the original data. Last but not least, I2P is mostly used for custom app communication and not for general web access. Which means that the usual browser fingerprinting exploits are even more reduced.

Whenever someone talks in defense of TOR: they are either naive, boomers or government employees, which are also the same dumbass crowd supporting "bitcoin".