Yeah - GIAA is the best post rock band for me. That's for sure. I am the biggest fan of this band. And I do adore post rock music a lot. Actually, I was in GIAA concert here, in Lithuania, in my study town - Vilnius in late November, last year. What a concert! I was jumping like a mad man!!! So much fun!
My the most favorite song of GIAA - Radau. It's absolutely mind blowing.
And yeah.. Forever Lost is a great, great tune!
I do like other post rock bands, such as: Caspian, Saxon Shore, Explosions in the Sky - great bands.