If you want your tone to be the same, but louder (like turning the Volume knob on your amp) then you probably want a "boost" pedal.
On the other hand, if you want your tone to change, emphasizing certain frequencies (like using the bass/mid/treble knobs on your amp) then you probably want an "EQ" pedal.
What kind of amp are you currently using? Can you get a tone you like, using just the controls on your amp? Or is something missing, you are looking for something "extra" that your amp can't do? Does your band use a sound guy and PA for gigs, or are you trying to mix the sound yourselves, from stage with your amps? Do you want the audience to hear the effects of the pedal, too, or is it just for your own monitoring purposes, so you can hear yourself better on stage?