I really liked the Nelson Freire's Brahms, but now I must really check out Kuerti's. I liked Freire fine enough on the D-minor, but in the B-flat, I kept comparing him to Emil Gilels, in which case Freire didn't fare so well... If you don't have the Brahms piano concerti, your best bet is getting the bargain 2-for-1 Gilels CD.
I saw Kissin play the B-flat live in Baltimore, & although I'm not a fan of his playing in general, he was electric that night.
For the D-minor, I grew up with the Pollini/Bohm LP, which I'm still fond of.