Munkeh111 on 09 January 2009
Xbox Live has M$ dedicated servers, which is what you are paying for, Sony relies on the publisher to provide the server. This should mean less lag, but I have only played 2 games on Live, and they both suffered from lag. The quality of the service does vary from game to game. The dedicated servers mean that in Call of Duty you can check your friends stats when they are offline, but I do not feel the extra price is worth it
As for XBLM and PSN, Marketplace has more content, though I do feel the PSN is better laid out
