The Krakens have two things going for them:
a) Looks amazing (esp the z series, but the x mirrors are nice)
b) NZXT has good build quality (should last ~5 years)
That said, you pay a high premium for them, and their cooling is a bit underwhelming.
GN Steve did a really good breakdown of most of the current AiOs last year in this review:
https://www.gamersnexus.net/hwreview...view-benchmark
Then he had a follow up when the EK came out:
https://www.gamersnexus.net/hwreview...liquid-coolers
All in all, the Kraken is a good cooler, there's no doubt about it (note most of these graphs rate the x72/x62 ones), it's on par with the EK/AC coolers in general use, but has louder fans and pump, and does a worse job cooling your VRM. Ultimately, the decision that swayed me to the ACII was the price, coupled with the performance. The ACLFII 360 was $190. Just absolutely bargain price for a quieter, cooler AIO.