If you're running a new business and want something that's way more user-friendly, Kick is the clear pick. It's modern, easy to use, and its integrations with Stripe, PayPal, and Mercury just work out of the box. You'll avoid the setup headaches that usually come with traditional accounting tools.
But if you need full accrual accounting, have heavy inventory, fixed assets, or a complex e-commerce setup, Kick just isn't ready for you yet. That's where Xero comes in. Xero is the better call if your business is more established, runs on an accrual basis, or has more complex needs. It's described as tried and tested, and it's especially strong for teams outside the US.
So if you're a new, cash-basis business looking for the simplest, cleanest experience, go with Kick. If your accounting is more advanced or you're operating internationally, Xero is the safer bet right now.