Zoom MSH-6

Really no complaints about it, does what it says on the box and does it very well.
Zoom has never disappointed me even tho I've only started to use their products recently.

It works great when recording ambients of any kind, but specially in a natural scene, and also acoustic instruments. I tried it on classical guitar and ukulele and it sounds crisp and clear.
A great option to replace a 2 mic setup for MS recording, making it extremely portable, easy to use and somewhat affordable, even considering that you obviously need the recorder itself to use it.