Hello people first post here!

I'm quite a noob in this domain so guess you could help me out. I want a better headunit for my car ( a tiny Chevy Kalos) as the current one doesn't even have CD support and i can't stand it anymore.

Current unit is a Blaupunkt. What would you suggest with a buget of 200$ let's say a maximum of 300$ if it's really good.
And could you explain me/direct me to some resources about what are the characteristics which make a unit produce quality sound (signal to noise, THD, internal DAC and the like i'm not really into it).

Thanks!