Hii, I'm using Asus Zenfone 5 with 2GB ram and 16GB rom. Overall, this smartphone is so good, no lag and had good performance on HD games. Multitasking is good too, with 2 gigs of ram which is big enough for me. And latest new from Asus, Zenfone 4,5,6 will get Lollipop update on mid May 2015...