Who each tool is really for
JustCall
JustCall belongs to the sales telephony category rather than the CRM category, and is generally chosen by teams whose day is organised around conversations: inbound queues, outbound calling blocks and text follow-up. Buyers who like it usually already own a CRM and want a better phone layer than it offers natively.
Kixie
Kixie occupies broadly the same space, and is likewise picked by calling-led sales teams who want faster dialling and tighter integration with an existing CRM. The honest position is that these two products compete closely, that both iterate quickly, and that the differences a comparison article claims today may not hold next quarter. Read both vendors' current documentation before you shortlist, and test with your own list rather than a demo list.