The GPU chip in all R9 280X cards are the same. The only difference is the PCB and cooler. Asus uses their DirectCU II cooler; MSI uses their Twin Frozr cooler; Gigabyte uses their 3x Windforce cooler; XFX uses their Double Dissipation cooler; Sapphire, which is left out, uses their Vapor-X, Dual-X, or Tri-X (Toxic) cooler; HIS, also left out, uses their IceQ X cooler; and Club3D, also left out, uses their royalKing cooler.
The best price/performance/temperature is Sapphire, followed by Gigabyte, and Asus.
The quietest one is Asus, followed by HIS, and Gigabyte.
The coolest one is HIS, followed by Sapphire Toxic, and Gigabyte.
Unfortunately, although HIS performs well at providing a very cool and quiet cooler, their performance drop is not worth the slight advantage. Their cooler is only 2-3C cooler than Sapphire and about 1 dbA louder than Asus, while being about 1 dbA quieter than Gigabyte. All of those can be marked down due to margin of error.
Based on that, I'll let you choose the one you want based on what stat is most important to you.