I used brown astro turf at first, when mine was a baby. I thought it looked a lot like sand. Then I switched to tile which I liked better for the ease of cleaning.
Now that he's 3, I use tile, but put a very fine layer of play sand on top, b/c he would poop and then lay in it (which beardies arent like leos in this manner they DONT CARE!) so the play sand helps to dry it out a little, and I scoop it out with a hermet crab litter scooper