Which of the Phantasy Star games do you think uses the best magic system?
PSI's system is pretty simple, but it does have the unique ability of talking to enemies. PSII was a lot more varied, with techs that were specialized against biomonsters and machines, but that made some characters less useful in parts of the game. PSIII was a bit unusual; I remember that some of the healing techs (mainly the antidote) constantly failed and sometimes had to be used several times. PSIV was a lot like PSII, but everyone seemed more varied and useful than in II.
Overall, I think I liked PSIV's the most, but I have to say PSIII's added an extra level of challenge to the game. A couple of times I got into a jam when I almost ran out of TP for healing.