I wouldn't want the three songs to give different effects, because it's the most rigid part of bard's rotation and if we had to plan the songs around buffing the party as well, it would cause nightmares and force us to make large personal dps sacrifices.

At the same time, the three songs giving the same buff effect is the SB situation, where bard just provides free damage utility that requires no real skill to capitalize on.

Therefore I think it's best that the three personal songs give no party buffs.