"Is there a favorite manufacturer used by most major Vegas casinos?"

Paul-Son has always had the lions share of the US casino business.
Bud Jones and Chipco were 2 and 3 in the US
Bourgogne et Grasset in France recently bought Paul-Son and Bud Jones. They are now selling all 3 types of chips.
Paul-son is a clay composite.
Bud Jones is plastic with a coin inlay for weight.
B&G and Chipco is sometimes refered to as ceramic chips but they are a clay/plastic composite.
Most casino quality chips run around 11 grams.
All 4 of the above have websites for more information.
There are a few other manufactures but they are minor players in the US.