Guitar or other plucked string instruments. It’s sometimes nice if pressure or slide brings in some kind of granular or delay effect, but not strictly necessary.
Guitar was my first instrument, and the one I still feel most connected to, even when playing an abstracted electronic form. There is also something about the layout and ergonomics of linnstrument that lends itself to guitar.
I’m also fond of mallet sounds on the linnstrument.
If you’ve got a nice velocity-responsive sharp attack, and then layer in some kind of pressure-sensitive pad or effect for sustain, this covers a lot of linnstrument’s expressive territory. And pitch bends also make sense for stringed instruments, as well as wind instruments to a lesser degree. So, upright bass, and woodwinds are also favorites.
I’m terrible at playing acoustic flute, but I sound halfway decent at it on a linnstrument.
I strongly recommend trying Roli’s Equator2. They’ve done the sound design for you. I love experimenting with MPE and I’ve found exciting sounds in all sorts of places, but if I just want to power up and play the way I would with an acoustic instrument, there are a few favorited patches in Equator2 that I can rely on to deliver with zero fuss.