It has to be said. No one is like Mahler! His sound/music is unique. The closest I can think of would be Hans Rott in his Symphony in E (Hyperion). Listen to this and you might think he is composing in Mahler's style, actually he preceeded him a tad.
That aside, if someone hasn't already mentioned it, listen to some Janacek (Simphonietta and Tarus Bulba), Suk (Asreal Symphony, Ripening, and Praga, as well as Serenade for Strings), and Lizst's Faust Symphony.
By the way you don't mention Mahler's 6th Symphony. Have you heard it? If not, do so - its manditory Mahler!
That aside, if someone hasn't already mentioned it, listen to some Janacek (Simphonietta and Tarus Bulba), Suk (Asreal Symphony, Ripening, and Praga, as well as Serenade for Strings), and Lizst's Faust Symphony.
By the way you don't mention Mahler's 6th Symphony. Have you heard it? If not, do so - its manditory Mahler!