The most common ones that I have used is Thompson or THK. I used these allot in my CNC Machine Design days. They both make excellent linear bearings. There are other manufacturers of these bearings, though if you tell them that you are looking for a compariable linear bearing to a Thompson or THK, they will know what you are talking about. Any motion control outfit carries them, WW Grainger & McMaster Carr as well (though more expensive at these 2 places).
Hope that this offers some additional assistance.
Kevin