@kenred2
Agreed on the missiles front!
Though if we must choose just between the two options... it'd have to be flamethrower.
Its a nice, insta-damage. Grenades are often on characters who could put out as much or more damage not using the ability, so I usually just regular attack with grenade wielders. Its harder to save/block both(or more with droids) attacks, and you have the added benefit of making the opponent chew up more force points if they're desperate to save their mini... Plus there's the chance of a crit, which is countered by the chance of missing entirely.
All of these points beat the grenades single save ability, which against force users is a simple forcepoint or bodyguard away.
By the by, IMO grenades should function more like W40K; save for half damage (rounded up). Then you could have sticky grenades, thermal detonators etc... haha