You'd think that'd be a subjective question! But science, as always, is here to poop the party, presenting "evidence" that shows which FPS games currently on the market draw the biggest "response" from players.
The research, conducted by San Francisco firm Emsense , looked at eight games - Battlefield 2142, Call of Duty 3, F.E.A.R., Gears of War, GRAW 2, Resistance, Halo 2 and Half-Life 2 - in order to measure "engagement and emotional and cognitive responses to content". Or, in other words, how much players got into it.
To determine this, the researchers used "proprietary brain monitoring EEG and bio-sensing technology" while tracking players engaged in the first 90 minutes of each game, and ended up with over 300 hours worth of data/
Their findings? That "the most successful FPS titles encourage close combat, dangling emotions of reward to compel players into high-risk, adrenaline-pumping scenarios". Think Gears' chainsaw duels, placing satchel charges on tanks in CoD, that sort of thing.
This means that, if you buy into the data, you can certainly draw a correlation between our involvement - and subsequent enjoyment of an FPS- and reviews scores/retail success. Gears of War has chainsaws and blood splatters. Halo 2 & 3 have insta-kill plasma swords. Half-Life 2 has the worlds greatest crowbar. Etc etc.
Shoot to Thrill: Bio-Sensory Reactions to 3D Shooting Games [Gamasutra]