When firms ask which accounting platform is "best" before outsourcing bookkeeping, it's usually the wrong question. The platform that matters is the one your clients are already on — a migration project is a separate decision from an outsourcing decision, and conflating the two adds risk and cost to something that should be simple.
QuickBooks (Online and Desktop)
The default for most US small-business clients, and the platform most outsourcing providers are deepest on. QuickBooks Online is generally easier to grant scoped, client-specific access to, which matters for confidentiality — see our security practices for why that matters.
Xero
Strong for multi-currency and clients with a more modern, integration-heavy stack (inventory apps, ecommerce connectors, payroll add-ons). If your client base skews toward ecommerce or service businesses that already use a lot of connected apps, Xero often requires less manual reconciliation work.
Sage and Odoo
Less common among small US practices but still widely used, particularly by clients with more established, larger-scale operations or international ties. An outsourcing partner should be comfortable in whichever of these your existing clients already run on — asking a client to migrate platforms just to make outsourcing easier is rarely worth the disruption.
The real decision
Pick an outsourcing partner based on their fluency across the platforms your clients already use, not the other way around. Platform migration, if it ever makes sense, should be a decision you make deliberately with your client — not a side effect of choosing a bookkeeping partner.