I own both the ZTE blade and Acer Liquid Metal. Out of the two, I much prefer the Acer Liquid Metal. As others have stated, the battery life is noticeably better, it is also a lot more snappier and more responsive. Although it's not to everyone's taste, I find the Acer UI very nice. The curved screen also works well and makes it appear that you've are using a bigger screen without distorting the display.
The ZTE has a larger homebrew ROM collection, but the Liquid Metal has newer official ROMs and the source code is available for homebrewing ROMs.