my top three abominations are:
#1: Counter-Strike: Condition Zero - the sucktacular aspect of this game isn't that it looks crappy (it ran on the old goldsource engine after all), but that it played as if it were thrown together in a matter of days by trained monkeys. took the concept of 'bad guy around every corner' to the next level

#2: Soldier of Fortune 2 - if they'd given you a choice between stealth and a shooting match, this might have made a decent game instead of long drawn-out reload-fest. never in the history of gaming has it taken so long to do so little

#3: this is really a toss-up between Pariah and Doom 3. Pariah made great use of the UT2 engine in the outdoor areas but then fucked it up with some less than riveting setpieces and retarded npc characters. Doom 3 also had great tech but wasted it on a predictable room-corridor-room-rinse-repeat concept set in semi-darkness and garnished with every cliche in the book
i couldn't find any screencaps that fully encapsulated the epic failure of these two games
p.s. why only FPS games? basically for comparison's sake. duke nukem: manhattan project vs MS train simulator = apples vs oranges