I pre-ordered Bioshock Big daddy box from the place that combines the two names. Used free postage option so had a delay there. But a friend got the game on day of release.
As for the other two places, when looking for Collector's Edition I just go with the cheapest, or if they have unique packaging (like with Neverwinter Nights 2) which I ever I prefer.
I know one had a cheaper Collector's Edition of World in Conflict, but now both have the same price as nearer release date. And Assassin's Creed (if the same contents) is also a lot cheaper at the one that was cheaper for WiC.
No idea if the reward card (that you have to pay for) sways your loyalty.