I doubt there is such a thing as the best rig period.
For me personally, two rigs stood out. One was a backline rig provided for the headliner of that evening.
The classic, infamous SVT+Fridge. It was brand new, the Heritage line. The bass player of the headliner had his soundcheck done prior to my arrival. I came there and brought my bass and cable. I looked around for the bass amp (was not hard to spot

) and this guy came towards me. He started telling me about gain and EQ settings while I was plugging in. I turned it on, hit two notes, looked at him and said 'nah, I'm good'. The amp was left with those exact settings. I was playing metal that night, as was the headliner. The sound was glorious. I especially liked how it was consistent all over the stage. The amp was sitting stage right and pointing towards stage left, like a sidefill. I fondly remember that gig.
The other is my own rig. It's two barefaced 12" cabinets and a poweramp of sorts (I mostly plug into the FX return of my Tonehammer or use a dedicated poweramp) The sound comes from my pedalboard, where the center piece is an old Sansamp pedal.
This gets louder than is safe for your ears and punches through the mix, yet sounds pleasant when I play at home.