I suspect the most convincing animations would involve a combination of both.
Second that..
But speaking of linear, (morphs), and rotational, (bones), i realise this to be true, BUT, morphs can be used ,with caution, for rotational purposes, tho more limited in the amount of possible rotation.
I've done a 3 part tut on building and animating eyes using morphs. They can work, but you do need to take special care with axis points being centered, and can easily add too much 'turn', which can really screw up after only about a 30 -45 degree rotation.
At the end of the day, i do prefer using a rig for eyes, but depends on situation. Sometimes morphed eyes are easier to work with during animation.
Re eyelids: Opening and closing eyes,/blinking, i've always used morphs for this, but then, my characters are far from realistic.....