I have always preferred the P models of the M series, no logo and a more robust LCD. My first new Leica was the M10, until then I had always purchased secondhand.
The new M10P has now been released. The shutter has been improved but M10 base module which I have has an excellent shutter the best of any digital M, but they say the new one is even better.
It also has an artificial horizon function and a touch screen. If you have an pre M10 version I would say is a no brainer to upgrade, but if you already have the M10 then I would say do not upgrade.
With the latest firmware the straight M10 is hard to beat.