Depends. Are you saying that you will only have 1 game to last you for a long time? Then Orange Box. It is far, far better on PC, and there is an astronomical amount of content that is PC only for TF2. But then again, your not already convinced to buy the Orange Box, so you are probably generally okay with having TF2 on Console: Its no where near as good, but it is still TF2. The main reason I would choose Orange Box is so you can get source, which means that you have a nearly infinite amount of mods you can play. If you can only have 1 game, it might as well be Half Life 2, since it effectively gets you infinate games. In reality, you should have just gotten the Half Life 2 pack on Steam for a ludicrous discount, and still had money left over for Crysis.
If you are a typical gamer who plans to buy another game or 2 in the near future, then get the Crysis pack, hands down. Its not quite as much content as Orange Box, but it will be all new, and it comes with a multiplayer game. Also, since you have Orange Box already, the content will be all new. Mods arn't quite as widespread, but there is some very good ones in the pipe (Mechwarrior: Living Legends comes to mind http://www.mechlivinglegends.net/component/option,com_frontpage/Itemid,1/). As a game, the Orange Box stuff is better designed, but Crysis is still very well designed if you can tolerate cheesy story and dialog. And whenever I get a new computer, I like to have a very pretty, graphics hog game to test it out, and Crysis is the benchmark.
Overall, since I am a strong proponent of mixing up your gaming diet, I have to say Crysis. There 2 fantastic sets of games, and are both very much worth playing. Its better to play both, rather then play 1 on a better platform. Besides, im sure some day soon Valve will sell the Orange Box for 10 bucks again. I would wait until then.