His 5th, 7th, and 9th are the most performed, w/the 10th's second movement being one of the most intense second movements of all time IMO. The 7th (Leningrad) is wonderfully brooding, w/the 5th and 9th being more upbeat (in the Russian sense). There is a great recording on Telarc of the Atlanta Symphony of the 5th and 9th w/awesome sonics.