I used to used Nice and Easy which lasted ages and covered grey really well, but they have since changed the formula and it barely lasts 5min. 
Currently use Nutrisse or a Swatzkoft brand and am leaning towards Nutrisse being the better permanent dye, but still loses its colour really quickly, especially around the roots. I wash my hair everyday as I need to.
Any suggestions? Am finding all the general toiletry products are turning to crap now and barely doing the job they are supposed to (loved Sure deodorant, but it is pants now). It's driving me nuts!