I have had the pleasure(?) of taking several of the state exams, and personally found the previous Texas Master Exam to be more difficult then the others I have taken. However, that was due to using some really poor prints as the basis for some of the questions. At least, you could comment on the questions, and all the questions with errors in the calculations (Wrong size EGC for the feeder breaker size) had comments. Florida's Electrical Contractors exam was difficult in only that they used up to 15 sources of information for the questions. I think it had a question that was "According to this book, what does this term mean?" and I didn't have that book with me, although I had 9 others. Oklahoma wasn't to bad, I scored 95% on the business portion due to being allowed the book that all the questions came from Again, simply checking the index to find the answer. I took Cedar Rapids, Iowa Masters before Iowa went state wide, as well as Michigan's Journeyman, and both of those were not too hard (89% for Iowa, 94% for Michigan).
As far as the requirements to take the exam, Michigan's is set up to deter nonresidents (by design, double digit unemployment numbers can do that) and the tougher apprentice requirements recently enacted have ended the lifetime apprentice. Florida's EC requires a pile of documentation as well as Board Approval, which seems a bit excessive. I think I got my Oklahoma Contractors maybe 2 days after I took the test, so either they are efficient with paperwork or they don't get very many people taking the test. It does amaze me the differences in state to state