I've looked pretty much everywhere but couldn't find a decent GTA V radio pack which includes all radio songs from PC version, preferably with commercials and DJ talk.

There's this soundtrack:
Thread 161945

It's almost perfect, but it has some missing tracks and some tracks are ripped from YouTube or SoundCloud.

Okay, looks like there's no such rip. Well, I'm going to make one on my own. I've already ripped all radio station from GTA and currently mixing the stations. So far, 5 stations are mixed.

Radio Los Santos
Space 103.2
West Coast Classics
Rebel Radio
Los Santos Rock Radio