With 4K displays running at $3K (?!!), the sweet spot in displays looks like the so called 2560x1440 display (compared with the 1920 x 1080 of 1080p fame). We are in the funny phase where the move to 4K is still too expensive with a gap to the 1080p which are$400 or so. So right now the gaps are. You really want IPS right now as they are really bright and nice.

• Asus VS274H-P. These are pretty much commodities now, the interesting ones are very fast for gaming running at 120 Hz. or even 144Hz. We have the VG248HE which is a wicked fast one.
• Monoprice IPS-Glass Panel Pro 27" is a good example. At just $456 (direct) it really breaks the pricing curves particularly if it needs collaboration. The big competition is Dell U2713HM (if you can stand the reliability issues that comes up on Amazon.com reviews) which you get for$540. And with Black Friday coming, they are already offering $10 off your next purchase if you spend$30. So a good idea to get a bunch of these.
• 4K Thunderbolt. Just waiting for a magnificent one from Apple when the Mac Pro actually ships.