I'll preface this post with: "I'm not a Ruger guy, generally." In fact, I own only one. Now, regarding a Model 77...
Quite a few years back I picked up via trade, a pristine, very early Model 77 with a tang safety, in .30-'06. I stuck it in the safe with the intention of trading it off, as the blue is gorgeous - deep and perfect, with no flaws. Even the trigger pull is crisp and light. It was in a Bell and Carlson synthetic stock, and the original stock was included. It's very plain wood with little figure.
Then I took it to the range. I was astounded with how well it shoots! Very decent, tight groups, no weird flyers at all! So, I stuck a Leupold 2-7 on it and it's still in my safe. It has been an excellent rifle over the years. I'm still planning on refinishing the stock to make it a little nicer.
They may not be expensive, but occasionally you're going to find one that really shoots well. Unfortunately, you won't know that until you get it to the range.
I guess that in most cases, I like old better than new. The American is newer and I don't know much about it. Good luck with whatever choice you make.