Took the AWS CSA - Pro Exam (just under the wire for the 2018 version). Only used these practice tests and and LinuxAcademy. Extremely helpful material.
After passing the Associate exam, I had a voucher for a free Amazon practice test, which I used after studying and exhausting all the practice tests. Scored a 65%.
Took the real exam 3 days later and scored a 77%. Whiz Labs was a great resource.