So you submitted to editors and agencies, and were rejected. They wrote a personalized rejection, though, praising certain elements of your book but deciding at the end it's "just not right for them." Well, good for you. You were close.
That said, do not, under any circumstances, include a rejection letter from another agent or a publishing house in your query letter to an agent. It doesn't help if you underline and/or highlight the line of praise; it's still a rejection and you definitely shouldn't be showing it to us. The time to mention what publishing houses rejected you (so that we don't resubmit) is AFTER we've taken you on as a client, and not before.
I don't know why people do this, but they do.
I'll be offline until Monday night for Passover, so don't expect a lot of comments to be approved between tonight and then unless I get a friend to do it for me. Enjoy, and Chag Sameach!