A lot of people are looking at the comparison between them based on what they have achieved.
I think they have both done very different, but really good things with their careers.
Look at Christian. Before he left the WWE for TNA, he had some momentum and I really feel that had he stayed, he would have broke through the glass ceiling sooner rather than later. His time in TNA was good for him, it allowed him to legitimise himself by winning the then NWA World Title and putting on some really solid matches in the process. That obviously helped his bartering when returning to the WWE. I really like Christian, always have, far more than Edge. That is not to say that Edge isn't better, but I have always found Christian to be more of a whole wrestler. Like it has been mentioned here, Christian has never been badly injured. And I still believe that Christian can make an impact in the WWE and win another big title.
Edge on the other hand has done everything. He is a nine-time champion and cuts a really good promo, and, although out of the hands of Christian, gets the better feuds. I just feel like Edge doesn't connect with me as a fan as much as Christian does. Sure he's a heel and he's not meant to keep me happy, but even when Jericho is berating fans I still feel that fan connection and I just don't with Edge.
Based on that, my vote is Christian, but not by much.