Skids weigh about as much as another adult passenger in your car.
The whole reason for skids is for protection, so in that regard, material, thickness, and coverage trump weight as a deciding factor for me. I went RCI over bud built, as they are 3/16" v 4mm (20% thicker), coverage about the same, and cheaper. Haven't done an oil change yet with them on, but I'd give the bud built the nod in that aspect, as it looks like they have a bigger panel. I've banged mine on the rocks a few times, and happy with the protection of the steel ones. Not a single soul bought these pigs for their fuel economy, and most everyone that bothers to put skids on had already put on a suspension upgrade that will easily handle all the weight that the GX is rated for, so I don't consider weight savings/less protection to be worth the cost for aluminum.