Well to start, Bad Company 2 shouldn't even be on that poll. It's an awesome game, but if Crysis 2 is a console port, BC2 is a pathetic excuse for even a console port (graphically speaking, and soft shadows don't change anything). Battlefield 3, sure, but BC2..nah. The only good thing I can say about BC2 is it's nice quad core utilization.
Metro 2033 successfully pulls off what it tries to show, but I think its incorrect to say that Crysis 2 uses DX11 effects to less of an extent than Metro 2033. In Metro, all DX11 does is make objects more round (like lamps, people's heads, etc.). Tesselation isn't applied exensively to the environment itself. In Crysis 2 tesselation increases the poly count of walls and makes the ground vastly more realistic, as well as the water.
In both games DX11 barely makes a difference, if you're just playing the game and not actually looking for differences, you wouldn't notice. Seriously, how many times do you go up to friendly AI to examine how round their arms are of go up to a brick wall to see if the bricks are flat or realistic. And at the core, both engines are DX9 engines with minor DX10/11 features patched on. Even BC2's FrostBite 1.5, which DICE proclaimed as designed from the ground up for DX10 and 11, look exactly the same but runs vastly better in DX9.
Both games could technically add more effects, including things from Compute Shader, bu as a whole it boils down to performance. To average 35 FPS at 1920x1080 in Crysis 2 Ultra settings, you need a GTX 480. And exactly how many people have GTX 480+ cards? Metro 2033 is also insanely hardware intensive. DX11 is fast, but I don't think its new features are streamlined yet. Just like DirectX 10. It brought a few new things, but it destroyed performance. It took DirectX 10.1 to fix DX 10's mistakes.
As for graphics in the 2 games. It's hard to compare. Metro 2033 has more individual detail, but Crysis 2 has more scale. It's about preferance imo. Do you like a ton of detail in your close surroundings or do you like vast beautiful scenery.
Crysis 2 has more potential as a whole though. Not as of now, but who knows what the modding community will do with CryEngine 3? If they make epic mods like Extreme Config and Real Lifesis like they did for Crysis 1, then for sure Crysis 2 will win.
I included BC2 mostly for **** and giggles.
You are correct, they are hard to compare since it is scale v. corridors... However from what I've seen, Metro does look better than Crysis 2 does.
Debating about hardware optimization could warrant a completely other topic... Both games fail to use multi-threaded rendering which is a DX11 exclusive feature and would massively boost performance. DX11 does have the tools to optimize, the problem lies within the developer themselves.. When a game is created console first, the developer looks at the PC platform and then throws on DX11 intensive features to please the enthusiast community instead of also using DX11 optimizations that must be coded for.
Hardware is a completely other thing... According to steam, the HD 5770 is the most popular video card, which is DX11... Therefore, optimizing for DX11 is certainly a profitable solution as long as the developer allows the end-user to enable and disable DX11 intensive features at their own will or have varying levels of say, how much objects will be tessellated.
For instance, Metro 2033 has options to disable both Tessellation and DoF while still running the game with the less intensive DX11 features... This ensures positive performance for mid-range 5770 users while also satisfying the enthusiast market consisting of GTX 480/570/580/HD 6970 users like me.
DX11 is still not used to its full potential in terms of optimizations and it is certainly not the failure DX10 was.
emperorCleon: I will purchase Crysis 2 when I fully see its worth when it hits below $25 so the DLC's bring it up to $45 and not over acceptable PC retail price.. Until it reaches that price, Crytek can kiss my ass.
On the other side, modders will most likely port over all the DLC maps for free so I have nothing to worry about other than getting the FY-71. ^-^