re: Best beginner acoustic guitar for an adult

I second Seagull and Eastman.

You can never go wrong with Yamaha, they tend to pack good value at all their price points, and they have guitars in every consumer's price point.

Breedlove, Washburn and Guild's import lines are worth consideration

Epiphone quality is inconsistent, including Masterbuilts. I've seen jewels and duds cross my bench. I would not buy an Epi unless I could put my hands on it first, and/or I had a bulletproof return/exchange policy.