Basically, what would you choose from the below...

1080p locked at 30hz / 900p unlocked at 30-60hz / 720p locked at 60hz


I'd go for 1080p locked at 30hz as it's a perfectly playable framerate and I'd prefer to have a nice clean crisp image.

why not both?
que Super Smash Bros WiiU

60 FPS should be more important. You can have a 1080p game, but if the FPS falls and rises uncontrollably, it will be a terrible game experience.

60fps. I'm starting to see that 30fps kinda looks like sh....

The goal is to have both. I'll turn off particle effects among other things before I'll lower the resolution. But if I can only have one... it'll be 1080p if I can have at the very least 30fps. Anything less and I'll lower the resolution to 1440 x 1080p.

I've been gaming on PCs for well over a decade and have 3X 1080p monitors in Nvidia surround resolution of 5980x1080p (bezel corrected 5760x1080). I also have a 120 hz monitor which I give a go from time to time.

At these resolutions gaming becomes a game of trade-offs.

Do I want full rez and 60 fps (or even 120)? Well I have to lower the game details and AA.

Do I want all details and AA turned on? I may lower the resolution to do so...

Does anyone ever want a dipping stuttering frame rate? No they dont... So don't give me the BS that variable frame rate is an OK tradeoff as long as resolution and details are high.

You should try out 120/144 fps some time, you would probably think of 60fps as "meh".
When I first tried out a 120hz monitor years ago, I spent probably half an hour just moving stuff around on the desktop because it was so silky smooth.

Pretty much.
However, the advantage the PC has is you can just throw more hardware at the performance problem.
You could achieve 120fps with everything on max in most games if you wen't with 3-4x Titans or Radeon 290's.
Basically, if you are willing to spend the cash, you can have zero compromises, where-as with consoles you are given what you get, regardless if you like it or not.

Besides on the PC, todays demanding game is essentially tomorrows solitair.

1080p honestly.

Don't worry, PS4 can do that.

Source: http://www.thesixthaxis.com/2013/02/03/pachter-reckons-ps4-can-render-games-at-240-fps/

Assuming 720p and 30 FPS is the default, 60 FPS. Because while both 720 and 1080 will look bad in ten or twenty years when 4k is the standard definition, 60 FPS is always going to look good.