Our favorite for low cost and friendly support is Atlanta-based OnPay Despite some quirkiness in the user interface, we've converted several small business clients over the past year and are far happier with this service than with any others we've used.
Gusto is second place given its affordability and great reviews from other users. We haven't implemented it for any of our clients, but those who have joined our practice already using it love it. Beginning November 2018 it will be a fully-integrated feature in the Xero cloud accounting platform.
And finally Intuit becomes more competitive by rolling out a rate reduction in November 2018. This makes their QuickBooks Online Full Service Payroll the lowest cost of our 3 options for businesses with more than 40 employees. For fewer than 41 employees, its selling point is same-day direct deposit which is not insignificant! This provides much needed breathing room versus the typical 2 to 4-day advance funding requirement for other online payroll service providers. Being fully-integrated with QuickBooks Online, its convenience and wholesale pricing deals make it a great option for many of our clients.
Email me if you have any questions or feedback about payroll for your small business.