Prioritize the GPU, RAM won't give you that much improvements since you already have a SSD.
I have 16 GB of RAM and none of the games use it. The only benefit of 16GB of RAM that I noticed is that loading of games for the second time takes lot less time since HDD data is buffered to RAM by Windows (I don't have an SSD).
Since you already have a SSD, I don't think you will notice that big an improvement as with a new GPU.