The top 3 as it stands are:

1. Call of Duty 4 6.32 Million Xbox360 and 3.49 Million PS3 (9.81 Million)
2. Halo 3 - 8.13 Million, Xbox360 exclusive
3. Gears of War 5.2 Million Xbox360 semixclusive

The number 1/2 positions are pretty secure at the moment, both Halo 3 and Call of Duty 4 are likely to add at least half a million in sales before the end of the year and its unlikely that the games coming out in the near future are going to supplant their level of sales for the time being.

The real question is, will Gears of War be supplanted on the number 3 spot and which game will do it?

The four games which have the biggest shot for that number 3 spot in order of likelihood.

1. Call of Duty 5 - Its coming out on PC, PS2, Wii, Xbox360, PS3 and it has all the name recognition behind it from Call of Duty 4. What it loses in focus, it makes up for in bredth.
2. Gears of War 2 - Xbox360 exclusive but it has a good chance of surpassing its prequel as the Xbox360 userbase is much larger this time around.
3. Resistance Fall of Man 2 - PS3 exclusive. It'll be bigger this time definately but the PS3 doesn't have as much of a history for huge sales on shooter titles, not enough anyway to give it more of a chance at the number 3 spot than GOW2.
4. Killzone 2 - this ones a long shot, its coming out early next year with no big holiday season push and it has to outsell the 3 rivals above and the Original Gears of War to stand on that number 3 position.

So what do you think?

So far IMO

Resistance 2 looks better than Killzone 2

1. CoD 4 Being multi-plat helped
2. Halo 3
3. May just stay Gears. Or maybe KZ2. But Resi 2 will have the holiday push and probable bundles.

err.. why isnt Crysis in there? or UT3 or other good FPSs? Oh i see your going by sales.... why?

Come on.  Having been rejected to a November launch, even on the off chance Killzone 2 is what Sony says it will be, do you really think it has a chance at 5+ million copies sold?

1. COD 4

2. halo 3

3. gears of war 1 or 2

edited because i thought it was about quality

I was talking about top 3 in sales, so I used the sales numbers... :)

if people knew how good cod4 (at least its online) was going to be and didnt fall for the halo 3 hype like all of us did, it would of sold more than halo 3 ( on xbox 360).

Whats a semixclusive squillam? :P

Gears isn't 360 exclusive, I have it installed on my PC right now (with extra levels!). As to best selling shooters, does Metal Gear Solid 4 not count as a shooter? It CAN be played that way if you want. If so I think MGS4 will be 3rd at the end of the day, or maybe Bioshock with total sales between PS3, 360 and PC. I doubt Gears will be one of the top 3 of this generation either in its first or second iteration. Call of Duty 4 will be number one until Call of Duty 5.

I think you changed that to semixclusive, so ignore my first sentence.