Here is a partial answer to my own question.
After googling around for a while I found a comparison between several
different transformers and discrete op-amps. It's a different preamp
circuit obviously but I found the test interesting.
Of the five transformers listed (with the ADK op-amp), my preference was
between the Cinemag and Jensen. The Jensen was smooth sounding, with a nice, full low end. The Cinemag seemed to bring up the high end a little more but was overall nice and full-sounding. The bass response on both sounded nice to my ears, too.