Quoted from Strohz:I've had good luck with teflon sliders on tile/concrete, but they do wear out eventually moving them around too. I bought these and been happy with them but don't move them a lot: http://www.marcospecialties.com/pinball-parts/LL25-EZG.
These are what I have and they are awesome. Even a widebody game slides like butter. Now, one of them did start to come loose, as in the the bottom part started to separate from the rest of the leg bolt, but I got some epoxy and now it seems very strong again.