Well i would take the ultimaker 2 if you have the cash, Its a great printer all around, very silent and you wont have to bother with it when you have it that much,

Robo3D has some problems, Problems that can be solved! But they are still problems,
Also i've heard that the stock hotend is pretty bad and you should replace it with another hotend asap.

So like i said, I personaly would go with the Ultimaker,
The first or the second, thats up to you,
If i could decide again, it would be a decision about money, If i had enough, i would take the ultimaker right away.