Maybe it doesn't matter to you all, but to me, the world of DCO was way to small, compared to CoX. Same problem with CO, neither could stack up. I played both DCO and CO, for enough time to top out a few characters. I was no power gamer in any MMO, but i remember the time it took to cap out a character in CoX felt challenging enough to invest myself in the toon itself. The other two games, I just didn't feel the attachment as my toons seemed to race to the cap. The only game I felt had similar grind/investment to CoX was World of Warcraft.
Again I was a casual gamer, but I just felt ripped of when I could top a toon out in less than 30 days of casual play. Casual play meaning at best 18hrs play across weekdays and intensive 16hr play on weekend days.
Mind you I was also an altoholic so I usually played what I was in the mood to play.