which would be better of the two, or should i run one on each.... any basic guides anwhere?
You can run both on each, provided they have the resources.
Tor exit node - this is the IP servers see when someone uses Tor
Tor obfsproxy bridge - needed for users in China where the GFC blocks Tor altogether
i2p node - i2p is like Tor if it only had hidden services.
freenet node - freenet is a distributed datastore - everyone stores some of the data (encrypted)