I've been flossing as well as brushing for years and had resigned myself to the way that the plaque still built up between my teeth between visits to the dentist, so that I always need a 'scrape and polish' as well as a check up.
Had a waterpik since reading about them on MN back in January this year and have been really pleased with the results. Ten months later the (small) gaps between my teeth have not filled up with plaque.
Once a day I do the full floss, waterpik then brush routine. Other times I just brush. I had hoped that waterpik would replace the tape / floss but having used plaque revealing tablets I've established that it takes all three in that order to get my teeth so clean that there is nothing to 'reveal'.
As a bonus, my gums no longer bleed.
The brushes never did anything for me, in-spite of being given a few for free most times when I visit the dentist.