Every illustration eventually shows you a rating. A++ from A.M. Best, AA+ from Standard and Poor's, Aa3 from Moody's. They're grading one specific thing, which is the carrier's ability to pay claims. Not the quality of the product, not the dividend history, not whether the policy was designed well for you.
The scales don't line up. A.M. Best's top grade is A++, then A+, then A, and their scale is built for insurers specifically. S&P and Fitch top out at AAA. Moody's uses Aaa. An A+ from Best is the second-highest grade on that scale, while an A+ from S&P is the fifth-highest. Same two characters, different meaning, and marketing material tends not to mention which agency issued it.
Two other numbers tell you more about a life carrier than the letter grade does. The risk-based capital ratio measures how much surplus the company holds against the risks on its books, and anything comfortably above 400% is strong. The Comdex score isn't a rating at all, it's a percentile ranking of a carrier's ratings across every agency that grades it, so a Comdex of 98 means only 2% of rated carriers score higher.
Ratings move slowly and they look backward. An agency downgrade usually follows a problem that showed up in the financials a year or two earlier. That's acceptable for the purpose, since a life carrier's obligation runs for fifty years and slow-moving stability is the thing being measured.
State guaranty associations sit behind all of this if a carrier does fail. Oregon's covers death benefits and cash value up to statutory limits per insured, and those limits get updated, so confirm the current numbers with the Oregon Life and Health Insurance Guaranty Association before you plan around them. It's a floor rather than a substitute for picking a solid company, and it's why very large amounts of coverage often get split across carriers.
Look the rating up yourself instead of taking it from a brochure. A.M. Best lets you search any carrier for free, and it shows the outlook alongside the grade, which tells you which direction the agency thinks things are heading.