I have three HZ30Wis, and they are great screens. One has a small problem (it needs switching off and on again every few days due to sudden appearance of coloured artifacts), but between them they have no dead pixels and haven't had any other major issues.
I wrote a summary of the HZ30Wi (
see here), but it's pretty worthless compared to Badass's review. Also did a summary of the HP ZR30W (
see here, but the same logic applies).
In short, the Dell is a great general purpose screen (OSD, lots of inputs and options), but it has a high input lag. The HP has a near-identical panel to the U3011, but is at heart a pure PC screen (few inputs, no OSD), with a very low input lag (ideal for gaming).
The Hazro is also a cut-down pure PC monitor, but with a slightly older panel. In all honesty, the difference in quality between the two panels is not as big as I was expecting, making the Hazro pretty good value in my eyes. This being said, you will get a much better support package with HP or Dell. Hazro's after-sales support is still pretty much non-existent.