For me the 0.0 pan law setting makes sense if you're keeping stereo tracks hard panned and mono tracks centered.
Having some level of attenuation in and towards center makes the pan-knob work a bit better IMO. -3dB is what I work with too. Just pick one and go with it, at least don't change it in the middle of a session
BTW Protools used -2.5 (newer versions I think you get to choose your self) and SSL 4k desks was around -4.5….