well it depends bigtime on what species you plan to keep. Many wrasse species will bury themselves at night or when spooked so having gravel for them could cut and bruise them when they go to bury themselves. Also, engineer gobies will dig out caverns and tunnels in your tank and sand would be much easier for them to build. These are just two examples of fish who would prefer sand. Sand will compact over time though and should be stirred every once and a while so that is its major disadvantage
As already pointed out to you more than once in your other posts 14G is too small for a sixline wrasse. Read this from this very site (apologies if you have since got a bigger tank)
In my opinion, I think it would look better with sand. And in the future if you should decided to get a substrate dwelling creature, you won't have to worry about changing the substrate.