Welcome to AA!
People grow corals under everything from 10K to 20K, so anywhere in there you should be good. Most people find what looks the best to them, i.e. what they like, and stick with that. There's been tons of studies for what's better, a higher or lower K
rating, but in everything I've read, there's nothing concrete as to which is better.
That blue is supposed to be there. Higher K
bulbs have more of a blue tint to them. Some people like more blue, some more white, some more yellow. Like I said, any bulbs in that range you'll be fine color wise.