Rapid ORM for Painless ASP.NET MVC Prototyping on SQL Server

What is a good ORM to use for rapid prototyping without the hurt?

I've used LINQ-to-SQL with great suc开发者_Go百科cess, but I always end up building a whole repository layer around it (and everything that entails) so I don't have to put "Insert/Update" and mapping logic in my controllers. If I want to add a column, I have to write migrations and update interfaces and repositories.

I'd like something that just works. db4o is a good candidate, but I've always had gripes with the lack of proper data paging and the cringing primary key support. So let's narrow it down to a SQL-based solution that works with SQL Server.

Which ORM can build a relational SQL database with the least amount of configuration or code?

Entity Framework is quite nice and with the latest release you get some nice features like Code First and POCO entities.

I would look at Fluent NHibernate as it is really quick to pick up and the fluent configuration is nice.

Entity Framework / Linq2SQL have the shortest time to market. NHibernate is a little more complicated.

I'd go with NHibernate anyway. When things get more complicated, it gets harder slower if that makes any sense.