Seems like Tor is better suited for browsing. Users don't need to run their own relay to use the network. Easy to bundle into a browser, etc.

I2P seems suited for infrastructure. If you're running P2P applications (torrents, nodes, message relays of any kind), Then you're going to be a spamming leech unless you're also running your own anonymity relay to support the network.

In Tor, you have to provide a contact email address to run a "trusted relay".

I2P is permissionless, everyone runs a relay.