What is better to move entirely: Parent-Part vs Model?

Hello!

I've recently stumbled upon something I have been asking to myself..

I want to make some characters with possibly animations for my game and I do not want to use an Humanoid-Object, because they only need to walk on one axis.

Is it more efficient to move a parent-Part with descending Parts? Or is a model more efficient in doing so?

Which one will possibly cause more lag? And are Parts that descend from the parent even possible to animate?

I thought that having to set CFrames with models is painful and always wondered why they do not simply have Vector3s like Parts do.

Thanks for answers!