I don't really agree that CoD4 was below Halo3, but there are plenty of people that would agree with that order based on new features like the forge or video sharing. I personally don't use those features really, and I vastly prefer CoD4 multiplayer to Halo3's. That has a lot to do with personal preference (it's not a "who can get that bash off first" game). As far as the single player game play, I liked both. I'm not sure that I can rate one over the other. Again with multiplayer, it seems like IF spent more time than Bungie on making the maps more refined. I can't say that I'm a huge fan of the halo3 maps, and after 3 iterations of halo, I can't say that I love having vehicles on such small maps. That being said, halo3 supports "social" 4 person multiplayer play, which is a huge benifit. I play CoD4 most of the time when I'm playing alone. However, I game with other people about half of the time. 4 of us can play halo3 on live at a time; however, this isn't possible with CoD4 (my biggest gripe).
As far as the rest of the rankings, there are certain games that I wouldn't have included on that list (pac man and such). Zelda definitely belongs... as does world of warcraft... and although I hate rock band and GH... those games belong on the list based on how many people do love them. I personally think that Mass Effect should have been a bit higher (above Assassin's Creed IMHO).
In any case, game rankings and reviews have a HUGE amount of personal preference in with them. You can't even base a game on sales anymore because of the amount of hype that was generated. In all honesty, if I just played by myself, I would have just rented Halo3 for the single player and stuck with CoD4 for multiplayer. However, because it was the third part in a trilogy of a set of games that I loved, I bought it at midnight when it came out.