I'm a commercial real estate agent in New York City. Even though your credit is very good, you may be able to increase it to 800 to qualify for the lowest interest rates.
Different credit agencies may have varying scores depending on how they calculate items within your credit history. Both 770 and 789 are very good scores and fall within the range of 740-800, which is classified "Very Good". Obviously, you have managed your credit excellently as it is already very good. However, you may be able to tweek it to raise it a few points to 800 to get the very top interest rates by doing the following.
First, if you haven't already done so, it's a good it's a good idea to look at your credit reports from all three reporting agencies, Exerpian, TransUnion and Equifax. The U.S. government requires that you can get one free credit report a year, so you can request a free report online. Be sure you use the link below because when you google it, there are so many imposters, it's hard to figure out what is what.
Also, myfico has suggestions how to improve credit. Someone with your score is no doubt doing practically everything right, but there are a few tips, such as not closing old credit card accounts (they show longevity of credit) and maintaining small balances that you pay off monthly. Also, it's a good idea to pay off all store accounts (e.g. Macy's) as they lower your score slightly. Here are some myfico pages that may be of help.
Hope this demystifies the credit score process and helps you get a better score, Barak.
Please let me know if I can be of further assistance.
Commercial Real Estate Agent