Ignoring multiplayer games as other people won't recognise those unique experiences, I'd say probably something from the CoD series. Infinity Ward do INTENSE incredibly well in terms of beach landings, stalingrad, and chaotic scenes in the modern warfare games.
It's actually quite staggering if you compare the best of IW's set pieces with the majority of FPS games, they just seem so artificial in comparison, in terms of lacking atmosphere around you. They are very, very good at pushing you down a rollercoaster path and making it feel like you are part of something bigger.
In fact CoD was that intense that it is one of very, very few games that I've completed less than a day after installing it, it just kept driving me forwards. Their games are actually quite short compared to some but the quality of the action is so high that I don't mind.