I like using 1, or 2 fingers for most chords. In the Yamaha if you only play 1 finger, you get a tonic only, with no 34d or 5th ... unless you use the no musical, ancient, baby Casio way (sorry - it bugs me) then a single note give a MAJ chord, add a Black key to the left for Min, and there's a thrid option for 7th, but I forgot it. That's against everything I ever learned in theory.
As a manual bass player, I never learned the really complex LH chords that many organists, and pianists use, so the sinple 1 finger maj - add the second finger to change Maj/Min and more than that, I have to use more fingers.