My Jazz bass mainly because it has such a nice feel to it. The neck is what i like most about it. If i could get that neck on my PJ i would be happy too.
Amp wise i'm never really totally satisfied. I have a combination of rigs and the only cab i love is my Berg HT322 because it does what its should and very nicely too. Its just a bit heavy. Aiming to try out the Mesa gear this year and hopefully the Subway range will answer my prayers for the ideal amp configuration.
Dave