While I personally think that Manhattan best replicates the type and rigor of quant questions, I didn't notice much of a difference between any sources on the verbal side. That being said, I only practiced verbal questions while taking practice tests and only on Manhattan, GMATPrep, and the OG diagnostic. I found Manhattan to be quite helpful on the CR side just on the high-level common mistakes / ways to think about how the test writers may be trying to mislead you. I didn't study nuanced SC rules at all, and just found focusing on meaning, reason, and thinking like the test writer went a long way (with a little bit of luck surely for a 51).