Gravel = PROS its ok looking, can look exceptional if you do it right. fish love to dig and burrow in the gravel, especially cichlids. Easy to hold plants down.
Gravel CONS =GETS VERY DIRTY with extended use, i know u can vacuum the gravel, but my vacuum just didnt cleana s much as i would have liked. If you are breeding , the fry can be lost in the pockets in the gravel. Gets algae on it, discolors.
Barebottom-PROS = CHEAP
BArebottom CONS = CHEAP/boring/fish cant burrow, doesnt bring out colors
Sand PROS = looks ritzy IMO. Cleaner looking, and cleaner PERIOD. Dirt doesnt collect under the layers of sand AS MUCH as the layers of gravel. The fish can still dig and burrow. allows easier cleaning, just get a hose, start a siphon and just put the siphoning end about an inch or two away from any dirt,crap,other waste and the siphon takes it right down without a problem. Comes in all colors
Sand CONS= Price. way more expensive then gravel if you get a AQUARIUM sand. Can get into your filter and ruin your impeller. Did it to mine, but you get abhout 5-6 months without having to change your impeller.
I dunno, i just love sand, id go with a black and blue sand combination, i bet that would make a JD show up very nice!!!