that looks great, my rx 480 8gb (samsung memory) performance is 22~24.5 MH/S at stock settings.
but why do people go with the AMD RX series and it have more popularity than nvidia, there must be a reason for this i guess..
Most miners go with AMD because it's been around longer for mining. Until more recently Nvidia support for mining was not very good. The cost per hash is generally better with AMD cards. With the latest 10 series GPU's, that is not as much the case any more and Nvidia is most certainly in the game.
The other reason miners like AMD cards is they are more hackable. To get the most out of the RX cards for ETH you have to adjust the memory timings in the Bios. You should easily be able to ~29 MH/s with just a memory timing mod.