Now I know why I did not find the Louis Glass Symphonies particularly memorable, indeed the performances were stillborn.
Its time somone with some pzazz to do the cycle..

Luiz De Cabos..

Neglected also implies they may have been recorded, but are not well-known due to a lack of advocates, or a defunct label. Although not a symphonist(only 3) most of William Mathias music went up in smoke with Nimbus, but this man is one of my top 10 composers. And Jaques Hetu's wonderful music and handfull of fine symphonies have have had limited distribution due to the Canadian government.

For starters:
Alexander Raichev's 6 symphonies
Andrei Eshpai's 9 Symphonies
Arnold Rosner's 8 symphonies (please..please)
Gerorge Rochberg's 6 symphonies
George Antheil's 6 symphonies

And certainly Jaques Hetu's 5!!

Juris Karlsons is very gifted Larvian composer, I think his Silver Veil is a masterpiece that should be heard by everyone.
Not much of his music has been posted.

Regarding Glass..
Even admirers of Phillip Glass will admit that his music is repetitous, boring to some..yet hypnotic to others.
When I fnd a Glass piece I like, it is usually shorter in duration. My favorite is the Concerto for 4 saxes not a dull moment in it..
..as for his symphonies..I keep saying OK..OK..I get it... I get it!!

Orthels music is great..If it were not for abysmally poor audio for most of his symphonies, he would be a favorite of many more.
The cycle is screaming to be redone...

I was surprised at the quailty of this music..a very endearing work..

While the 12 symphonies of Alexander Moyzes are a uniquely tonal delight to traverse, IMHO none of them approach the status of masterpiece except the 7th. It is essentally an extended lament for his daughter who died at an early age. (A very unique masterpiece, not of a angry of howling protest against fate, but a tender, loving nuturing of the precious moments that only memories of love can bring.) Very refreshing for these troubled,unloving and narcissistic times.

But I had not realized the depth of this gifted composer until I had heard his other orchestral compositions, several of which are posted here.
If you have not explored the easily accessable music of Moyzes, you are in for a treat. Some of his 13 symphonies are posted on Youtube. You can hear the wonderfully tender 7th here:
https://www.youtube.com/watch?v=GIeDswxpmkw&playnext=1&list=PLTjs0r9R-ubN3KN4ioWeH-b89fsuOQR7r&feature=results_video

There is also the fabulous Anna Karenina Suite that you can listen to here:
Better than Rio Grande, IMHO..

http://www.youtube.com/watch?v=t76F4N2o2RA