In some ways I2p is more secure, but it has its own pros and cons. It’s primarily used with services & sites within its own network, similar to onion sites, and used that way it’s said to be faster than Tor. It can be used for torrenting with a client that supports it, like qBittorrent or BiglyBT, without harming the network. There are outproxies you can use if you want to anonymize access to normal websites, but there’s only a few of them, and it’s slow. You can have it and Tor running at the same time without them interfering with each other, though.

Feather is open source and has Tor built in.

It’s more similar to tor than a vpn.

Figure out what qualities you want in an OS, pick out a few distros that have those qualities, and make usb sticks that you can live boot. Use each one as though it was your actual system for a few days and get a feel for it. Then install the one that you like best, or go back to the drawing board. But pick one that suits you, not one that meets someone else’s needs.