Being someone who hasn't had much experience with hair colour in the process of getting my hair the shade of blue I wanted I tried quite a few different dyes. The two that I was best impressed by is Crazy Colour - Sky Blue and Bleach London - Out of the blue which I will write about with in another post.
I'm really impressed with the quality of colour you achieve with with this brand as I wanted a more dark blue and all the other blues I'd used previously left my hair more turquoise. As soon as I opened this dye I understood the mistake I had been making, this dye is a warm blue which means its closer to purple on the colour reel. Originally I didn't want to bleach my hair but in the end I caved in, I'm glad I did now as the results are 100% better. I'd say the dye lasts on bleached hair 3-4 weeks when washing once or twice a week and a high pigmentation the faded colour isn't terrible but obv not what your after.
The only issue is DO NOT HAVE A WHITE PILLOWCASE!! My pillowcase now has a lovely blue hue to it which isn't the end of the world but still just something to take into consideration. Also if your like me and ridiculously messy its really easy to get off your neck head ears (pillowcase).
It is a fantastic dye great for experimenting and belows my example :)