The BEST for color is Helios... And they seem to be easier to find currently (was hard for a while). However the Helios DE units have had quality control issues in the past for some users, which is a shame, as it really is a lovely blue bulb that makes colors POP and look greatâ€"really the best blue DE bulb out there...
five is right in that the AB 20K is lovely for color too, but has less PAR than most other blue bulbs...
Phoenix's are very nice too (and as blue as any 20K), very bright with high PAR, but tend to wash out reds and pinks...