Hardware.Info posted a review on the HP Z34c, LG 34UC99, Philips 349X7FJEW, and Samsung C34F791 monitors A quote from the article:

Wide is beautiful - that is, according to the enthusiasts. To be clear: we are talking about monitors in the so-called ultrawide category. We already received quite a few requests to test the Samsung C34F791 and our readings asked the same question for the Philips 349X7FJEW. Today cater to those people and also cover two other interestings, very comparable models: the HP Z34c and the LG 34UC99. 

Although Samsung very recently made a statement with the C49HG90 that 32:9 is also a valid screen ratio, with ultrawide we still talk about 21:9 or - hello purists - 43:18 ratio of models with a resolution of 2560x1080 or even better, as is the case with the monitors that we are talking about here, 3440x1440 pixels. In the latter case these are usually distributed across a surface with a diagonal area of 34 or 35 inch, depending on the origin of the used panel.

 HP Z34c, LG 34UC99, Philips 349X7FJEW, Samsung C34F791 review: four times ultrawide