The commentator above lives in the area where Turkish/Muslim heritage/influence is still strong so her opinion could be right for that area only (Sandak/Raka oblast).
So, lets start with festivals:
EXIT Festival (with Sea Dance Festival in Montenegro) - encompassing various music styles spread over several stages, it attracts around 600000 festival goers in recent times
Guča Trumpet Festival - held for over half a century, the greatest gathering of trumpet players and festival goers on Earth - about 600000 people come into a 2000 people strong town for several days of brass band music
Belgrade Beer Fest - between 600000 and 900000 people visit it for cheep beer and some mainstream music (rock, reggae, pop, hip-hop...)
Gitarijada - Guitar fest, held for almost half a century in Zaječar, hosting young and unaffirmed bands, as well as proper rock bands from Balkans and Europe (dunno about audience numbers)
Nišville Jazz Fest - held for 20-30 years, where traditional and ''assimilated'' jazz is performed, attracting players and audience from everywhere.
To sum it up: Electronic, Rock and Jazz are played on the best festivals held in Serbia
Beside aforementioned genres, the also popular ones are: Pop, Hip-hop, Turbo-folk (from the comment above), Pop-folk. There is also traditional/folk music, still strong, played at celebrations of various kinds, as well as in old school kafanas - rural (izvorna) and urban (starogradska).
Traditional instruments still in use: trumpet, frula, accordion, tamburica, violin...
Check the rest here
