I have it narrowed down to two.
Dell Ultrasharp U2715H ($559 on Amazon)
ASUS PB278Q ($432 on Amazon)
I love the thinner bezels of the Dell, but I also love the cheaper price tag on the ASUS.
I've also seen a lot of reports of bad light bleed and uneven backlighting on the Dells. Haven't seen too much bad stuff on the ASUS.
- Consider the much cheaper 25" U2515H. It's identical to the 27" except for the screen size.
Those two really are some of the best 1440p monitors you can buy outside of professional hardware.
My 25" is perfect with respect to bleed and backlight as far as I can make out.
When I was looking into a monitor to buy, I believe I looked at that same ASUS. And it looks to be quite nice. What put me off, if I recall correctly, was primarily the design and the price (the U2515H is much cheaper). The UltraSharps look miles better in my opinion, and actually match the Mac aesthetic quite well, whereas the ASUS looks too much like a black PC. But that may just be my personal bias.
And yes, the thin bezels are amazing.
Also consider the DisplayPort 1.2 daisy chaining capabilities of the Dells, which the ASUS does not have. Though that doesn't work properly in OS X (but does in Windows, I believe), so that might be a moot point.
On the plus side of the ASUS, it has slightly better colours (100% vs. 99% sRGB) but a lower brightness (300 vs. 350 cd/m2).