I never heard both coins xtrabytes and safex.
I don't recommend you to trade on the coins which have a low volume because you will be difficult to make a profit.
It is better to select the coin which has middle until big volume so you can see your chance to make a profit.
Maybe you can choose any coin from the top 100 coins list so you will find the profitable coins.
It is too difficult if you still force yourself to buy and sell those coins and I don't think that you will make a profit from both coins.
But we could only give you advice as you need to decide which coins you want to trade and we could hope that you don't make a wrong selection of the coins.
But even if you choose the big volume of the coin, it doesn't give you a guarantee to make a profit because that will depends on how you trade and your skills in trading.