“Guitar and Vocal” can be quite demanding when it comes to sound “quality”.
You may find some useful suggestions here: Sound Card Reviews
The ART USB pre-amps look and sound pretty good for the price - I don’t have one, but I’ve heard quite a few recording samples that have used a high quality recording microphone with an ART USB pre-amp. I have a UCA202, but that only has “line level” inputs, so not really suitable for you (unless you have a mixing desk).