I would rarely disagree with Bruce, but I do agree with willovercome. If you are looking for a nice woody sound with not a lot of the subtle complexities of sound the acoustic can have then the 57 will do the trick. Some people use it in combination with other mics. By itself on solo acoustic I find the 57 rather dull. In a mix it can do fine, and you can also use it on guitar cabs and percussion, so it is a very versatile mic.
However, for a single mic on solo acoustic or in sparse arrangements where you really want to hear the acoustic, the MXL603 is the best IMO.
I like the Oktava also, and you can buy an additional omni cap for it. So it is a great value.
The ECM8000 has served me well in combination with the 603 on some recordings. I wouldn't use it by itself unless it's all I had.