Welcome to the site!
While I agree that Phantasy Star IV is the best in the series, I can't agree that the others are "bad" in comparison, especially when you've never played the other games and therefore can't make that conclusion to begin with. It's like saying chocolate is gross based upon appearances only when you've never tried it.
Yes, that is the analogy I'm using for now. Deal with it.
Phantasy Star I was the first game I played in the series -- I actually played it when it was first out in stores for the original SEGA gaming platform -- and the game itself seriously warped my mind. To me, the game was
that amazing. An example of this: I used to be able to run a mile in six minutes, and the music from that game would play in my mind as I ran, and kept me going!
Er, I know that sounds insane, but the game was an obsession for me - srsly. LOL.
Anyway, my point is, if anyone snubs the other PS games based upon appearances only, they are missing out. I still get a kick out of the quotes from the games... "You are a fool! You will die!" to the hilarious liar- reputation of the Dezorians.
PSII is beautifully complicated, but makes you feel so many emotions, that it is similar to PSIV in that aspect.
The least favorite of the series for most "phans" is probably PSIII since it is sort of a departure from the rest of the games, however - it is fun, campy, and seriously entertaining - because you get to marry a bunch of different people and have different directions of the game (and therefore the fate of the game itself).