Best persistence, object-relational mapping, data-access layer generation tool?

As this is a frequently asked question, and since we have here some people that may have used such tools, maybe it'd interesting to ask the question again and synthesize opinions.

What is the best persistence, or object-relational mapping, or data-access layer generation tool?

In fact the goal is not to define the best tool, but to point out the advantages and limitations of the tools you used. This would help other developers in the process of deciding which tool is best adapted to their own situation.
I have been asked by e-mail:

It is really nice to have a complete tool list, but the thing is, there are too much
available there.

Which product is the best persistent product for .net, in your mind?
Or could you recommend several?

I am not able to reply by myself, so this requires some collective work... Feel free to comment the way you want (comments, posts or e-mail). I would aggregate the results in a story.

If this works out well, we could do the same thing for other categories of tools.

Update: I started to aggregate opininions.
Update: Yves Reynhout tells us how to select an object-to-relational-database mapper.