The Erudition one is the best F2P cone for that path, although we are ALLEGEDLY getting an Erudition Herta cone at some point but who knows.
The others I think are more character dependent. For example the Hunt one is really good for Topaz and only loses to maxed out Swordplay or 5* cones, but it's garbage for Ratio. The Harmony one is basically just for Gallagher.
Oh also don't buy all 5 copies from the currency store. Several of them are quest rewards for finding all the hidden birds in a Penacony area, some come from the clockie statue, so check first. I know there's one Erudition cone you can get that way.
I definitely did not forget to put the 2020 GOTD Guru winner,
azuarc
in my sig!
https://www.backloggd.com/u/HDT/