What was easy for him on a keyboard was sometimes very difficult when played on a four string bass. One of the reasons the Doors bass lines are so melodic is because he approached the bass using a linear keyboard versus the four bass strings aligned on a neck. The Doors keyboardist, Ray Manzarek, played both keyboard and bass in the Door songs. One issue not many consider is how difficult it is for a keyboard player to duplicate the playing style of a guitar player. What it boils down to is the 'best' choice will be influenced by how you intend to use the virtual instrument. Some create better rhythm sounds while others are intended for lead. Do you want realistic Taylor or Martin acoustic steel strings, acoustic nylon strings, acoustic 12 strings, Les Paul electric guitar, Fender Stratocaster electric guitar, Fender Telecaster electric guitar. You didn't mention in your query what kind of guitar sounds are you seeking.
