It's mostly a personal choice on look ... but PFS looks amazing as a substrate, I feel it really gives a tank a more realistic look than just gravel. I also feel it benefits plants a bit better by giving the roots more substrate to anchor to ... IMO.
Do not go with Play sand as it can cloud up very easily when disturbed. PFS is small enough to actually look like a sand bed, but large enough that it settles back quickly when disturbed. The hardest part about sand is rinsing off the fine dust ... when I add PFS to my tank (add about a cup full every two weeks to slowly build up sand under my gravel) I boil it about 3 times. Amazing how much dust comes off when you boil sand.