Gravel IMO is easier to maintain with less fuss. It's better suited for those new to fish keeping because it requires less work. I just set up a tank for the first time with Caribsea white sand and although it looks pretty nice, the fine sand gets everywhere at first (and after my PWC's). Depending on how fine the sand is, I can imagine that it can get sucked up by your filter too and reduce the life of the impeller. Moreover, it takes extra work and care to clean (i.e. hovering a siphon just over it to clean up detritus), whereas my tank with gravel requires less finesse and a straightforward gravel vacuuming. Conversely, the sand does allow you see the waste easily to remove. I suppose in the end, they both have pros and cons. It's just a matter of how much extra work you're willing to put in to your tank to achieve & maintain a certain appearance to your taste.