I don't think you can definitively rank the exclusives. Amazon aside they've all had their ups and downs. Ness had a bad start with all the server issues, but Shulk was pretty great. Weeks of pre-orders and the large window for the second shipment both online and in-store. Rosalina was terrible online, but in-store both Rosalina and Jigglypuff were fine, and Jigglypuff got a lot of time online after launch. TRU has gotten the most in-store numbers by far, but there's few of them, Lucario was horrendous as far as pre-orders went, and Greninja had some cancellations. Walmart was fairly good with Gold Mario, not spectacular, not bad.
Best Buy's definitely still at the bottom for now though. Meta Knight sucked. But maybe Dark Pit will be good.