It seems to have been unanimously decided that for magers and meleers, deadly red spiders are the way to go.

Unfortunately, they are not effective for training ranged and I'd like to know If anyone has found a decent monster/location to train at in the eoc?

Lessers are weak to ranged now. The best setup is:

 

Blue d'hide coif

Blue d'hide top, bottom and vembraces.

Batwing boots

Power amulet

Explorer's Ring (optional, but it gives a +2 Prayer boost and allows you to high alch drops)

Magic shieldbow and shortbow

Rune arrows.

 

Primarily use the shortbow, but bring the shieldbow so you can switch and use Rejuvenate. Just make sure you wait until Rejuvenate finishes before switching back.