Two-time entrepreneur seeks accounting software

I am both a service provider and a landlord, and I am looking for accounting software with bookkeeping functions for my two companies in the IT and accommodation sectors. The solution should be “simple,” as I write “simply structured” invoices with only a few invoice items or even articles.

The software I am looking for should meet the following requirements:

• Create e-invoices
• Free text can be entered for invoicing (free text field)
• Optional dunning process
• Multi-client capable
• Preparatory accounting with DATEV interface
• Account management
• SKR 03 and SKR 04 chart of accounts, posting to accounts (SKR - Standard chart of accounts, Germany)
• Creation of individual accounts
• P&L
• Sales
• As simple as possible, user-friendly
• On-premises preferred

One software workstation is planned. MS Windows systems are used.