Quote Originally Posted by Adrian II
Artificial intelligence is nice, human intelligence is a far better opponent than any machine and groups working together are smarter than soloists.

Sooo, the answer is Battlefield2.

Nothing beats a few rounds on a BF2 64 ticket map in a six-member squad with a squad leader who is Medic and has VoiP, no noobs on board and every member knows the map and can fly, drive and use anti-tank or C4. Gets my adrenaline going every time.
You have a good point, and I indeed prefer human opposition in most cases. But there are situations in which human opposition is not a good idea: when I want to be able to play when I feel like it, when I want to play a non-mainstream or old game that has lost/never had any notable mp community, and when I want to play complex long-time campaigns that would be too much fuss to arrange with others, etc.