Like others said it's really down to preference, but from a sub drivers point of view (never played the other units in DW) for me SC with SCX has the edge over DW. I like the additional units that SCX provides, having said that I like the quick mission generator that DW has. However, there is one thing in DW, even though some would consider it minor, that has always bugged me and that is dead platforms disappear after a short time, why I'm not sure. In SC they remain in game and in shallow water engagements can attract active torpedoes. Soon after buying SC I remember playing the mission 'Command Challenge' and watching my Mk48 torp that I had fired at an LA class boat being pulled off course by a dead TR-1700 sub sitting on the bottom
. In theory in shallow waters you could use a dead unit to evade incoming torpedoes.
The bottom line is that I enjoy both sims and they will remain on my hard drive for sometime to come.
Nemo