good hair dye for unnatural colors?

i want to dye my hair a dark purple or a navy kind of blue and i need a good hair dye that can last long. i have magenta hair right now, i use loreal hi-color highlights and the color lasts pretty long, almost 2 months. I hate splat and i don't really like manic panic, i know it has lots of cool colors but after one wash, the color faded terribly for both hair dyes. i'm looking into star gazer and pravana chroma silk but i was wondering if anybody has other recommendations? i know crazy hair colors don't last long no matter what but i really want to find a brand that lasts atleast a month since the one i use now doesn't have the color i want.