Real-Time Shopify Accounting Sync

I need my Shopify store to feed both sales and customer data straight into an accounting platform in real-time. I have not committed to QuickBooks, Xero, or FreshBooks yet, so I’m open to whichever of those three you feel will provide the most seamless and reliable integration... (Budget: $30 - $250 USD, Jobs: Accounting, Excel, Microsoft SQL Server, PHP, Shopify Development, Software Development)