Seeking a monitor for Photography editing

Looking for recommendations on a monitor for editing in Photoshop and Lightroom. Using it as an external display off my MacBook Pro. I do not game, or really even watch movies/videos on my computer. I've been looking at Dell's Ultrasharp line - came across the U2415 but it looks like it may be an older version. Recommendations? I'd like to stick between 24-27" and $600 or less.