Direction shades with best staying power

Rose Red (and probably all darker pinks in most brands)
Turquoise. Especially the latest batch. Stains like billy-o!
Maybe Alpine Green? I've not really used that much so I can't remember!

I only have experience with their pinks and purples, but hope this can be of help.

I've found a lot of the staying power was dependent on the condition or porosity of my hair, and leaving on under a plastic cap/clingfilm wrap, as with all brands except SFX - which I can hardly ever get out! I got the best staying power from Cerise and Flamingo Pink on a light ginger bleached base..about 3-4 weeks maximum, depending on how often I washed. The cerise faded to a nice colour, but I did find Flamingo went peachy (due to the base colour more than anything else). When used on a yellow base the Flamingo stayed brighter for longer and also faded to a better candy pink hue.

I found that Lavender and Lilac had very little staying power when I used them over a very pale bleached base. The Lilac actually washed out within two washes. I retried, with heat and leaving on for as long as possible, but like many of the Crazy Colour ones I've tried, they just didn't take 🙁

Hope some of this is of help 🙂

I would say Plum, Rubine, Midnight Blue, Rose Red, Turquoise, are all long lasting.
On the other end of the scale, Violet, Lilac  and Lagoon Blue are the least long lasting IME.

Rose Red, Plum, Midnight Blue. Although Midnight Blue faded to green pretty quickly on my hair.. but the dye itself lasted a lot. Turquoise and Neon Blue too.

I have noticed how fast Midnight Blue fades to a greeny shade and overlaid it with Neon Blue which seems quite sticky.  Violet doesn't last but is a lush fade colour, total pastel gorgeousness!!

Midnight Blue, Neon Blue... I also found Apple Green to have good staying power.