aragonite(not cc, but fine grained sand), IMO is the best choice for a dsb, however it is not always affordable to most of us, or even available, but if you can, i would use aragonite over a silica based sand
an d my vote is also for the dsb(also, if you have any inhabitants, as mentioned, it is much more difficult to make the change, which most do)
ps, welcome aboard, it is a great addiction, and this is a great source for info