Steve has done a lot with Kermit and Ernie (not to mention Rizzo the Rat), and he is a great singer ("One More Sleep 'Til Christmas" from the Muppet Christmas Carol is one of Kermit's finest performances, in my opinion). But I'd say Jim was better because he was more versatile and also put more of his heart into each song. There's a sense of longing in "I Don't Want to Live on the Moon" that can't be heard anywhere else, and a unique sense of quiet contemplation in "Being Green" that has made it an anthem of pride. Jim could do calm, pensive songs as well as outrageously wacky and wild songs like "Captain Vegetable," "I Never Harmed an Onion," and "Tenderly."