... at least for gaming, the winner is 3 x 30" LCDs pivoted to portrait mode, according to MaximumPC magazine in 2011:
I don't have this setup but tried pivoting (smaller) monitors before (work apps, not games). I hit these issues:
1. Mainstream monitors (22"-24") are too narrow for some websites or applications
2. The 'Colour inversion' effect
This is worst with TN panels.You basically need the panel more or less perfectly vertical and have to look at it dead-on.
Even with TFT IPS panels, there's something a tiny bit 'off' that I can't put my finger on - its as if colour reproduction was designed to be optimal in landscape mode. Or something different about pixel spacing, or how sub-pixel colour elements stack up next to each other... Just guessing here.
3. For desktop use, you end up bobbing your head up and down.