Well, United States rules the music world, followed by the UK and I guess Australia.
Countries like France, italy and Germany are in their own bubble, but that's mostly since they push music in their own language rather than English and that's the reason why they don't hit the global charts.
Spanish music is really breaking into the charts along with South Korean music, but after that I would definitely go towards Scandinavia (primarily Sweden and Iceland, followed by Norway and Denmark), if I were to pick who's setting the pop trends across Europe.
If you ever have free time, there's definitely a lot of Icelandic music that's worth a listen.