The two best RGB keyboards to date which offer a wide range of colous are of course the K70 and blackwidow from what I know
you can check out the "Corsair Strafe Keybaord" which sells at a really decent price, HOWEVER its backlighting is only avaible in red color :/ And I havent done my research to figure out if it supports other specific keys...
Unfortunately for your oponion, the razer blackwidow could be your best bet
To be fair the black widow has a MUCH MUCH more friendly and easier system (synapse 2.0) to use
The blackwidow compared to the Corsair K70 has a much better vibrant colour which makes it pop out more
The only thing about the blackwidow keybaord which I dont like its the plastic build compared to corsair which has a much better material, HOWEVER if you treat a blackwidow keyboard nice, it can last for years
TBH dont pay attention to the brand, blackwidow Razer is spectacular, Yes I do admit a lot of children that have a lot of cash to spend do own one, but PLease dont let that change your oponion for the worse, its actually a really good keyboard, and everyone should be proud of owning either the Corsair K70 or the Razer Blackwidow, at least be fortunate!!
(unless someone has a better idea, or finds something better for your needs)