How about Marina md20? Please recommend the guitar.

If it is not placed in extreme environment, the general panel will rarely crack and bulge.

Yamaha FG730 is a classic, but there are many imitations. Of the three models you mentioned, Marina MD20 is definitely recommended. This model has high cost performance, good quality and workmanship, and excellent fingering and singing skills. I suggest you take a look at this famous article "Ning Miao's Green Piano Guitar Must See". There are detailed comparisons and introductions, such as materials, missing corners, pickup trucks, etc. Baidu can find it in a moment, I hope it will help you.