I think the vocal sound quality is fine; it seems to me that the guitar sound is weak, so you might focus more on that.
If you want higher fidelity for cheap (these could be used for anything, including vocals), I can recommend an EV635a, or the Naiant Omni mics.
After those, you might consider checking out one of these (none of which, I actually own):
Shinybox (or other) ribbon mic.
FYI, I own an ADKTC and an AT4050 (I used to own a dragonfly), and I doubt that any these would significantly improve your existing sound.
FYI, to hear a 635a and SM7 (along with a ton of other mics, including Neumann, Soundelux) check out this thread: Samples of 19 Various Mics - SM7, Elux, M149, R84, etc.