Hi vinaypro,
Both of them are excellent boards. the tipping factor may be that Gigabyte has a reputation for having the strictest manufacturing standards in the industry.They also tend to have somewhat better heat dissipation due to more copper being used in the PCB. The Gigabyte GA-EX58 UD3r is a better overclocker (if your into that) and has slightly less power consumption. other than those two areas they run a dead heat in performance. you will be pleased with either of them ,however, being at the same price point i would recommend the Gigabyte.