I use Q line. Mainly because I still have some left after buying a ton of it a few years ago (like 5 spools).
It's hard to beat the Ozone or Flexi pre-packed stuff. I think both are rated at 660 plus. Flexi has a 20, 5 extension package.

A Q line spool is cool if you fix bridles a lot and stuff like that. I originally got into it when flying the foils and routinely replacing bridles.
In terms of just replacing flying lines, it's more user friendly to go pre packed with great company line like O and F, in my opinion.