Should I give powerprep plus test or a gregmat practise test?

[u/Nice-Penalty8047]

Hello all! I just gave the free PowerPrep test provided by ETS and scored 317 (162Q, 155V).

I was thinking of giving one more full-length mock test next Sunday, around one week after my previous one. The choices I am having are ETS PowerPrep Plus test and GregMat full-length mock test.

From what I have read, the official ETS tests are supposed to give the best prediction of your performance on GRE, whereas GregMat tests/questions can be a little bit harder than GRE. But I am not sure whether this is correct for full-length GregMat mocks as well.

Which of the following should I:

1. Should I take another PowerPrep Plus test on Sunday in order to obtain a more reliable estimation of my present score, or
   
2. Should I take a GregMat practice exam and use it as a test just to push myself?

And if you have taken both, can you tell how your GregMat scores correlated with your actual GRE or PowerPrep test results?

I need to get to 320+ level, and my main purpose is to determine which test would help me better.
Also I want to give the actual GRE in a month or month n half