I would like to know your opinion about that, what mapping strategie do you use, what do you prefer and what are the advantage of each ?

I prefer mapping files. I personally dont like placing attributes on the class describing how the class is to be persisted.

I feel like the mapping file gives my an easy view of all the mappings related to persistence of the entity without having to look through the class to detemine which sql column a field is mapped to.

If you are building a new application, then I think that using Attributes is simpler and far less verbose.

And note that you can save the generated mapping streams and stop using attributes at any moment.