This may not be the most insightful response you get, but I'll share my story anyway. I did all kinds of research up front on which test, but in the end, the local tester I chose only uses the WISC and didn't give me an option. When I switched tactics and went with a real expert in PG, I found that they looked at the kids and chose the best tests for me. What is more, but picking a real expert, I didn't feel like I had to make that call. It costs money and for us it required travel, but it is one way to answer the question: choose the tester rather than the test.
Maybe others have more insight into the different tests.
Mary