Why not get Kelvin and use RGB fan? EK XLC Predator and Swiftech H series offer better pump (better flowrate and liquid static pressure head) and perhaps better radiator performance, I'm not aware if Kelvin sourced from Alphacool, if so, at least Kelvin's pump may last longer than Kraken pump.
If you felt that RGB add instant aesthetic on your build, go get it. Kelvin is expandable, you can use different fiitings tube and rad+fans, it won't be as stellar as Kraken but with little creativity you can use Nickle plated tube, borosillicate glass tube, and PETG + add some color dye or UV additive to loop.