I use the Line Audio CM4 (which replaced my KM184) due to the ruler flat frequency response. The lack of low cut does require extra room treatment.
The EV-RE20 on lower bout works wonders on the low end (stole the technique from Pat Metheny). A tube LDC would also work but I wanted something more rugged for travel.
I use this combo through a modified Focusrite 4th gen (thanks to Revive Audio, who upgraded the I/O compontents). I use minimal processing (my PuigChild does the heavy lifting) and one my clients (Discovery Channel) is loving it. Of course, were talking about 'wallpaper music' heard behind dialogue/location recordings... but I digress
As for capturing singing and playing at the same time, this Steve Albini vid favors the AEA Ribbon on vocals a Beyer M130 ribbon mic,and some DIY soundboard mics on guitar - nice technique:
https://www.youtube.com/watch?v=Ualm3rCZRz0