They are pretty much functionally the same.
Cdparanoia may be better if your discs are scratched/dirty/ or otherwise difficult to read:
In addition to simple reading, cdparanoia adds extra-robust data verification, synchronization, error handling and scratch reconstruction capability.
Cdda2wav has built-in cddb support (ie: freecddb). As Grip covers this for you, it may be important only if you are running directly from the CLI.