What is the best acoustic guitar for beginner? It all depends who use this guitar and what kind music the player is interesting for. Before buying, you should know something about acoustic guitar size and types.
Basically, people choose acoustic guitar according to the age of the player. If the player is too short or too tall, adjust to choose the right one.
4-6 years old 1/4 size
7-8 years old 2/4 size
9-10 years old 3/4 size
11-adult full size
Another thing you should consider is that acoustic some acoustic guitars are using steel string while others are using nylon strings, for example, classical guitars and flamingo guitars. If the player want learn classical or flamingo guitar then choose the nylon string guitar, otherwise buy the steel string guitar which is very versatile for music styles like folk, country, blues, jazz or rock.
The most important thing you must think about is the budget. Don’t buy the too cheap guitar, believe me. Set your budget around 200 dollars is reasonable. Buy the best within your budget because the too cheap guitars are not guitar, they are toys. The bad sound will make you give up guitar for you can't see your improvement of your skills.
Buying a good guitar is a complicate stuff. You should consider the sound quality, the action, the playability and the craftsmanship. It is a hard job for beginners. My suggestion is go after the trusted brand like Yamaha, Takamine or Epiphone. All these brands have good quality control and offer entry-level products at affordable prices.