Something similar to Mahler

Of course, Mahler 2nd symphony is the closest link to the 3rd. The 1st is a lightweight introduction compared to the 2nd. Mahler very much rooted in the central european - Austrian-Czech-Jewish tradition, so you really should look after composers coming from this tradition. Dvorak and smetana to a certain extent kin to Mahler in their recurring to folk songs in their large symphonic works. You should also hear some Hungarian composer. Karoly Goldmark is an interesting composer, his major opera, the Queen of Saba you can order from Hungaroton label. And of course, Bartok.

Thanks for all the input. I'm a Big Orchestra fan. Honestly, I do have complete list of Mahler symphonies. Also Bruckner and Shostakovich. Shos is another favorite, however I wouldn't compare to Mahler since I found the 2 composers are very different from each other.
Bruckner is pretty close, especially symphony 4, however Mahler is more emotion and less "attack" compare to Bruckner.
The reason I picked 3 and 5 cause I found them most sensible and beautiful pieces from Mahler. Of cours other are wonderful too, like the 4,8 or 9, but they are on a different scale.
Smetana is great and of course "ma vlast" is always the most beautiful song for me. I'm not familiar with Karoly Goldmark, but will give it a try.
Alexander Nevsky is pretty powerful as well. R.Strauss, Holst (the planets) are very "attack" and "fire"...
Again, what is most closest to Mahler 3 or 5? Especially 5?
:)

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!

Try Schoenberg's Verklarte Nacht. You'll be pleasantly surprised how beautiful and romantic this piece is.

Liszt Faust Symphony. Very good idea. Hear the version of Ivan Fischer, BFZ, Philips.