have had the ratchet halfords pro range, some of them doubles for some time. No issues with them above the 13 mm even on tough jobs but below sizes for example the 10mm and 8mm do not use them on seized bolts etc as the ratchet does not take much to wreck and they get pricey to replace as singles.
I have only one flex head as a recent purchase, not made mind up yet as for general use but it has made one job a lot easier at least so far.