Degeneration X was a reaction to the nWo. nWo was the first of the two and really revolutionised wrestling. Before the nWo there was never a faction anything like it, and I always found them to be better than DX - well at the very start of their being anyway. I always liked that they were more vicious, more violent, more focused and so on. DX was just about a bunch of guys being together as friends. nWo was about grouping together to gain power. They were focused on taking out everyone (eliminating their competition), taking all the WCW titles and then holding the WCW up for ransom. They were like a separate company (and this is more evident at the start with Ted Dibiase in there) that was trying to takeover the WCW by force, until the nWo owned all WCW assets. It was a better concept and it was worked to perfection.
As more guys were added to the picture and as guys like Dibiase, Giant and Waltman were removed it lost a lot of its direction. And eventually it got old, failing to reinvent itself by having the younger guys move up the nWo ranks. This is where DX didn't fail - as DX made a lot of younger guys stars in their own right. HHH was nothing before DX, X-Pac found a new level of success there, and Billy and BG got over something stupid. DX was also more innovative towards the end, which they were able to do with their over-the-top stuff. The nWo could never do the sought of stuff DX did because of Time Warner standards and practices. Bottom line is that IMO overall nWo was better and overall did more for the professional wrestling industry than anything else in the history of the business. It was revolutionary and it really changed the game, spawning numerous rip-offs and spin-offs ever since.