HP Envy x2 vs Dell XPS 12 vs Asus Taichi 21:Who is the best?

W.A.Khan,                                                                                                                                                                                                                                                                                                                 HP Envy x2                                                                                                                                                 The Envy x2 impressed us. Its outstanding industrial design really shows the potential of a tablet/laptop hybrid. The HP Envy x2 has a clean, comfortable design and feels lightweight in tablet form. It has excellent battery life, and works just as well as a laptop as it does as a tablet.
But, The laptop mode is top-heavy, and the awkward tablet detachment mechanism isn’t perfect; it has limited ports; and a slower Atom processor means in performance it's far behind most ultrabooks, even though it’s priced like one.
The bottom line: The HP Envy x2’s capacity to be a full Windows 8 tablet or dock with a keyboard works as well as advertised, provided you’re willing to live with slower performance at a high price. You’re paying for style.
Windows 8 (32-bit); 1.8GHz Intel Atom Z2760; 2GB DDR2 SDRAM 1,066MHz; 747MB (Total) Intel GMA; 64GB SSD             Processor 1.8GHz Intel Atom Z2760
Memory 2GB, 1,066MHz DDR2
Hard drive 64GB SSD
Graphics Intel GMA
Operating system Windows 8
Dimensions (WD) 11.9x8.1 inches
Height 0.6-0.7 inch
Screen size (diagonal) 11.6 inches
System weight / Weight with AC adapter 3.1 pounds / 3.6 pounds (tablet + keyboard)
Category Ultraportable hybrid                                                                                                                     Price; $849                                                                                                                                                                                                                                                                                                                     VS                                                                                                                                                             Dell XPS 12                                                                                                                                                 The Dell XPS 12 is a thin, powerful, very cleverly designed touch-screen convertible that flips into multiple screen positions.
But, For all the hype about touch and tablets with Windows 8, the XPS 12 still works better as a laptop than as a slate. Its battery life is on the low side.
The bottom line: Dell has revamped its rotating Duo laptop concept into the much-improved XPS 12, but like most convertibles, it makes a better laptop than tablet.
Windows 8 (64-bit); 1.9GHz Intel Core i7-3517U; 8GB DDR3 SDRAM 1,333MHz; 32MB (Shared) Intel HD 4000; 256GB Lite-On IT SSD                                                                                                           Specifications
ProcessorIntel 3rd Gen Core i5 3317U / 2.6 GHz
Memory4 GB
Hard Drive128 GB
Operating SystemMicrosoft Windows 8
Display Type12.5 in
Max Resolution1920 x 1080
Graphics ProcessorIntel HD 4000
Weight3.35 lbs                                                                                                                                          Price;$1,199.99                                                                                                                                          VS                                                                                                                                                           Asus Taichi 21                                                                                                                                           The Asus Taichi 21 offers a clever implementation of a dual-screen design in a slim Core i7 chassis.
But, Only one of the screens is touch-enabled, which feels like a major oversight. There are probably only a handful of situations where you'd need an outward-facing display.
The bottom line: More of a clever proof-of-concept than a practical product, the Asus Taichi still delivers on its basic promise, combining two displays for a unique take on the laptop/tablet/hybrid genre.                      Specifications
ProcessorIntel 3rd Gen Core i7 3517U / 1.9 GHz( Dual-Core )
Memory4 GB
Hard Drive256 GB- Serial ATA-600
Operating SystemMicrosoft Windows 8
Display Type11.6 inIPS
Max Resolution1920 x 1080 ( Full HD )
Graphics ProcessorIntel HD Graphics 4000
Optical DriveNone                                                                                                                                      Price;$1,489.00 to $1,599.00