Architecture with Web APIs using Dapper

I’m developing a restful web api using MVC 5, We are using Dapper for the data access layer, our business logic is managed by a BL layer, my web api is structured as following :

• ApiControllers
• Models
• ModelBuilder

The DL returns DTO after a validation by BL. ModelBuilder are building Pocos from DTO using AutoMaper, the pocos are converted to json in the actions

which pattern do you think is better to use to build my pocos ? Thanks in advance