Which framework is better for productivity and easy for maintenance ?

I am not familiar with Dapper.

Both Dapper and Entity Framework are ORMs. The primary purpose of an ORM is to make developers more efficient. They are designed to eliminate the need for programmers to do low-level stuff without sacrificing machine efficiency. I think you can trust ORMs to be efficient for the computer too.

I consider Entity Framework to be more difficult to learn than ADO.Net but the time spent learning EF is very much worthwhile. EF will save you time in the future. ADO.Net is probably more difficult to learn for advanced stuff that EF would make things easier for.

Comparison: ADO.NET vs Entity Framework Core vs Dapper

For Your Case (ERP in ASP.NET Core 8)

You’re dealing with multi-entity, relational, transactional data (like SalesHeader ? SalesDetails, PurchaseHeader ? PurchaseDetails).
Here’s the ideal approach ??

Best Balanced Choice: EF Core + Stored Procedures (Hybrid Approach)

• Use Entity Framework Core for:

  • CRUD operations

  • Model binding and change tracking

  • Maintainability and faster development

• Use Stored Procedures / Raw SQL / Dapper for:

  • Heavy queries (e.g., reports, large joins, aggregations)

  • Bulk inserts or updates

  • Performance-critical modules

This hybrid pattern gives:

Productivity of EF Core + Performance of Dapper/ADO.NET

Example Setup

// EF Core for normal operationsvar order = new SalesOrder {
    Header = header,
    Details = detailList
};
_context.SalesOrders.Add(order);
await _context.SaveChangesAsync();

// Dapper for heavy reportsusing var connection = new SqlConnection(connString);
var result = connection.Query(
    "EXEC GetSalesReport @FromDate, @ToDate",
    new { FromDate, ToDate });

Recommendation Summary

Final Answer:

Use Entity Framework Core (EF Core) as your main framework — it’s the best for productivity and maintainability in ERP apps.
For specific performance-heavy queries, integrate Dapper or stored procedures.
This gives you both speed and developer efficiency.