Which of these GTX 760s should I get?

The GIGABYTE would be my first choice, but I would say just go for whichever has the better deal, they are all good brands with good coolers.

I agree with the above choice. Here's the Newegg link:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814127745

I own the MSI Geforce GTX 760 GAMING OC. When I checked all the reviews before purchasing, it had one or so degree less than the 2nd coolest (can't remember which) but what blew me away was the noise: it was much less.

I'd get the MSI version if I were you, but I guess that's because I own one and can't recommend anything else. I can however guarantee you won't regret getting this card.

I've been creating a list of fixes for game problems and solutions. Just thought I'd throw it in. If you think some of it might prove handy you might wish to copy it to a file.

Common fixes:
- games without VSYNC can have it forced usually in the NVidia Control Panel
- games without Anti-Aliasing can have it forced usually in the NCP

1. Witcher #1:
- VSYNC must be forced through NVidia Control Panel (run game, close game then open NCP->Manage 3D Settings... and the game will show up in a list so you don't need to search for the link).
- game STUTTERS with hyperthreading enabled (disable in BIOS if you have it such as an i7-3770).

2. Batman AC
- disable PhysX and DX11 (they cause severe stutter, small performance drop and visual improvement is minimal.)
*Game can crash, particularly at Mr. Freeze battle due to NVidia drivers. You can Google that if needed, switch to the recommended drivers then switch back after the battle. I had no further problems.

3. Kingdoms of Amalur Reckoning (great fighting)
- 2560x1440 causes no text at times

4. Fallout 3, Fallout NV, Oblivion
- change iFPSCLAMP=0 so 0 is refresh rate (i.e. 60). Make sure VSYNC is enabled and you hardly drop below 60 (deviating causes weird slowdowns or speedups).
*The improvement is simply incredible. I can't remember if I had to change the INI file in the Documents folder, main game folder or both. You can GOOGLE for which file to change if interested.

5. Dead Space #1
- force VSYNC (same as Witcher). This enables default refresh (i.e. 60FPS) instead of 30FPS. NCP setting overrides in-game setting.

6. GTA 4
- never fixed. stupid game synchs to 44FPS at 1920x1080 and below or 52FPS at 2560x1440. So broken. Tried everything. Play Saints Row 3 or 4 instead.

7. Metro 2033
- no issues per say, but tweaking takes time. DOF for example is very demanding and should be disabled.

8. Prototype #1
- USB devices can slow game. Use game controller, run FRAPS to see frame rate and then UNPLUG keyboard, mouse to see if any effect (30% improvement for me by unplugging keyboard).
- 2GB of VRAM forces game to default settings affecting AA and resolution. There's a FIX on the net to overwrite a certain file that forces to your desktop resolution.
- AA can be sorted by forcing in NVidia Control Panel.
- I think there is actually a fourth issue but I forget.
*Prototype is still a great game though. Didn't like Prototype #2 as much. Prettier though.

9. Far Cry 3, tweaking hints
- do NOT enable anti-aliasing. There is good AA already by default. Using AA really hurts performance and doesn't add much visually.
- VSYNC and GPU buffer settings probably should be set to ONE or you get stuttering.
- play around with settings to achieve 60FPS or game can get sluggish.
- My RESOLUTION had to be fixed every time. May not affect anybody without higher than 1920x1080 but I had to CHANGE the resolution to any other then back again to 2560x1440 every time I started the game again.

10. Bastion
- I added "-nofixedstep" to the launch options (set launch options) in Steam. No quotation marks.

11. The Sims 3
- serious stuttering. I think I just forced the HALF VSYNC method and it improved a lot (30FPS instead of 60FPS).

12. Spiderman Web of Shadows (surprisingly good game IMO).
- disable Hyperthreading or it is unplayable. massive, massive stutter and slow.

13. Skyrim
- recommend the UNOFFICIAL PATCHES http://skyrim.nexusmods.com/mods/19/? (other unofficial patches at bottom)
I also use THESE:
- SKYUI (needs SKSE; Skyui is a must-have. truly awesome)
- SFO
- SFO Expanded Diversity
- W.A.T.E.R. (or "Realistic Water Two" and "Realistic Water Two Legendary")
- Official HD Texture Pack

*I used the Nexus Mod Manager for several games (need to login to the nexus website). Also, some mods have patches that you do NOT update you just apply so it overwrites.