Black Ops was a fun single player, not the worst this gen, and I rated ODST so low because of it's weak singleplayer.

I did factor in other non online parts like co-op and splitscreen play, cause that's what makes Halo 3, Reach and the left for dead games so special.

And singleplayer on the Killzone games are really meh, from the sloppy cover controls (which is why they aren't used in multiplayer) to the WWII in space story, and it's not like a living breathing world like you can get out of the Half-life games or the action movie feel of both CoD4 and GoldenEye.

I did throw 1943 in there by accident but it popped into my head when I was thinking about quality shooters as I spent a lot of time with that one.

The Mass Effects and the Bioshocks.  I would also give Gears 1/2 a run if you have a 360 (although one is out on PC as well).

But seriously, Mass Effect and Bioshock are two of the best new IP's we've seen in years.

If you looking for a shooter with good story here are some that come to mind....

Bioshock, Half-Life 2, Bulletstorm, The Chronicles of Riddick, Halo Reach, Resistance: Fall of Man.

Those are a handful of the more interesting ones.

Half Life 2 (and the Episodes) are the king of FPS SP campaigns.  You need to get yourself the Orange Box.  Also, set up a Steam account and get Half Life Source - it'll run on pretty much any PC and while the graphics are dated it remains a fantastic SP campaign.

Really, very few - if any - SP campaigns seem able to match the Half Life series for innovation.  Most modern FPS just take elements from it and apply the 'make it bigger' principle but they don't actually add anything new really.

The Orange Box plays pretty well on 360, too, and you get Portal as well, the best - if short - FPS campaign (with no shooting though) of recent years.

Killzone 2 & Killzone 3 don`t have great stories. Killzone 2 is anabove average shooter primarily hyped up due to its graphics and Killzone 3 while more heavy on the action and has a more cinematic feel to it...the story is just dull for the most part. The whole story is all about 2 Helgast generals fighting over power nothing more. Its the action in the game that keeps it interesting not the story.

I will say this...if you do choose to play Killzone 2 or 3 you are definitely better off with Killzone 3. More cinematic, better action sequences and feels more fluid. Just don`t be expecting much out of the story.

I'd rent it first, the novelty of the ageing wore off after about an hour or two, the first hour I've played I was under impression that it was the funnest game ever, after that the novelty wore off and I got into the grind.

So, I am going at it 3 games at a time.  A quick overview of my thoughts:

Crysis 2:  Still amazing.  This is one of the best gaming experience I have had.  I am sold, call me a fan.

Metro 2033:  So far, I am loving it.  The atmosphere is amazing.  Everything has a meaning, the safe zone are really interesting.  For the first time, I feel that a game as mastered the art of Survival horror.  But man, this game is hard.

Call of duty 4: modern warfare:  Well, I don't feel "immersed" in the game.  I feel that my partners are doing way too much work.  I just tag along, going along with them.  Weird.  I don't hate it by any means, I just don't know if I am playing it or not.  Maybe I need to get used to it.

Borderlands GOTY is only $20 at Gamestop. Buy it. Now.

EDIT: Nevermind, it is $40 in Canada.

Great single player FPS's is Bioshock 1&2 (The first is a lot better, but the second is still good), Halo Reach, Halo 3, Halo ODST, Half-Life 2(Get the Orange Box), Singluarity, Metro 2033, COD4, Crysis 2( Just beat it), Borderland, Prey, Left4Dead 1&2, Killzone 2 (haven't played 3 yet), and COD2. 

Borderlands and Bioshock.