as i contemplate my next rod, i am trying to decide what weight to get

i have a 9' 9wt, and 8'6" 5wt
i am debating between a 7'6" 4wt or 3wt

looking for a small stream/panfish rod, but dont want to limit myself.
never know when that bluegill will turn into a bass.

help me decide, i dont know enuff about the limitations of each weight