I tested traditional drawer slides, bearings, and Ultra-High Molecular Weight (UHMW) slides. I took a poll of 27 likely buyers as to their feelings on the best way to open and close the drawers. We all came to the same conclusion, which happened to be the most expensive (doh!) - UHMW.
Now I've seen several drawers built that slide on top of strips of UHMW, with varying degrees of satisfaction, but finding these pieces that are specifically designed and extruded to work with the T-slot channels was my eureka moment for this project. If it hadn't been for the cost I would never have even asked the question what was best. These account for $90 of the build cost, but they're worth it.
For those unfamiliar, UHMW is a super plastic. It is 'self-lubricating' like PTFE but with much more abrasion resistance, is used in armor, climbing equipment, as the surface for artificial ice rinks, and a whole lot more. The wiki article
is a great read.
They are lighter (1.1 lbs vs 24 lbs for 2 good drawer slides), have no moving parts to gum up or rattle, do not slide open on their own on a hill like drawer slides, lock the drawers in place to eliminate shifting, and only take 3/16" on each side instead of the 3/4" for traditional slides.
On that last item, the space isn't trivial. Saving 9/16" per side allows wider drawers: 4 sides * 9/16" is an extra 2-1/4" of drawer space. With drawers 40" long and 8" tall that's an extra 720 cubic inches of volume you get in your drawers because of these slides!