As the title says, I'm wondering which bolt is better to use.

They both cost the same amount of parts (if I recall correctly) and have similar effects (freezing/mobilizing enemies), though the Freeze Bolt seems the better options, as it can kill weaker enemies and does some damage, anyway, too.

It also seems, at least in my experience, that the Shock Bolt doesn't last as long and the bolt can be shot off enemies to un-freeze them.

Maybe I'm missing something, but they seem so similar that the Freeze Bolt makes the Shock Bolt redundant.

Perhaps I am mistaken, but can't the shock bolt affect various enemies, whereas the freeze bolt only freezes 1? I don't know why I've thought that, but because of it I have found shock bolts more useful when encountering several enemies, whereas I use freezebolts for bosses.

You could be right. However, the Freeze Bolt can freeze multiple enemies and it can be upgraded to increase the area of effect.

On the other hand, the Shock Bolts can be upgraded to stun enemies for longer, rather than increasing area of effect.