I have both. The 340PD has the better trigger pull. I think its due to the lighter weight cylinder.

Still, if I had to pick one, it would be the M&P.

I think Smith got it really right on the M&P. Highly durable finish. Big front tritium sight. Light but heavy enough to shoot.

For me, the M&P ticks all the boxes I want in a pocket able J-frame.

Still, I can't bring myself to sell the PD as it is also an excellent revolver and a marvel of technology.