Schreiner's commentary is in need of revision, since he has changed his position on imputation. He didn't believe that imputation was a correct way of looking at justification when he wrote his Romans commentary. He changed by the time he wrote his theology of Paul. Hopefully, he will revise the Romans commentary sometime. In terms of solid, Reformed commentary, you cannot do better than Murray and Haldane. Murray's commentary never went to a second edition of which I am aware. The new edition is only an exact reprinting. I would recommend Moo, not because he is fully Reformed (he isn't), but because he is just about the only solid commentary on Romans who interacts with (and refutes) the New Perspective on Paul. Moo is also off in his interpretation of chapter 7, in my opinion. But Moo is also encyclopedic. Cranfield is also of exceptional quality (his strength is in laying out the arguments for various positions fairly and clearly). However, it is a very technical commentary. I'm surprised no one has mentioned Morris's good contribution to the Pillar series, which I would recommend. Shedd's commentary is outstanding. In fact, the late S. Lewis Johnson thought that Shedd's commentary was the best one out there (Johnson taught through the Greek text of Romans at least 15 times). Anders Nygren has written a commentary that helps greatly with the flow of argumentation. Hodge's commentary is also very sound, although Murray has picked up on all the best insights of Hodge. Stott and Barnett would be very good on the more popular side. I understand that Guy Waters might eventually write a commentary on Romans. Watch out for that one if it comes!