Flush is probably better. Brake fluid accumulated a bit of water over time, I flush mine every 3rd season. Flushing is easier than bleeding as there should be no air in a working system -- you're just displacing old fluid by pushing new fluid from the reservoir thru the lines and out the caliper.
Tips:
- Always use a new sealed container of fluid. An open container will gradually absorb humidity snd be as 'wet' as the stuff you are flushing out.
- A cheapie speed bleeder or brake bleeder bottle makes this easy for one person.
- Do back, front, and clutch if it's hydraulic.