Depending on the level and your luck, you can get lame items or pretty good items (such as stacks of chaos and Nature runes, and mithril equipment).
Refer to the link below for more information.
considering anchous can weaken you and i forget they might be aggressive i would go with cockroach soldiers and plus cockroach soldiers can drop rune scimitar witch sell for around 30k right now.
* Cockroach workers * Cockroach soldiers * Ankous * Catablepons * Dark Wizards * Ice Warriors * Ice Giants * Moss Giants * Hill Giants
Lesser Demons can drop about 20 at a time,also cockroach workers to the west of Varrock can drop a few. Or you could just kill the fire mages right near the port town.
in runescape, you can find coal in the dwarven mines, the alkharid mines, barbarian village, some places in the wilderness, and cockroach workers and drones drop 1-2 noted coal.
the drop rate is on chance but i belive it is a rare drop from them
Cockroach Soldiers drop a wide variety of items in RuneScape and have since been less killed as a better alternative, Grotworms, has opened up after a recent update. Cockroach Soldiers now always drop Carapace, which can be crafted for crafting experience. Cockroach Soldiers do have access to the rare drop tables, but offer fairly invaluable regular drop items and therefore are not killed as commonly any more due to newer and better monsters.
infernal mages drop 7 blood runes and death runes commonly.dark wizards drop all runes nearly every drop.lots of slayer tasks will drop runes.Cockroach drones commonly drop air, water, earth and fire runes. Cockroach workers also (uncommonly) drop nature, chaos and even cosmic runes. Cockroach Soldiers drop death runes (and if your a member rare blood runes) and a few others. The flesh crawlers found in the second level of the Barbarian Stronghold commonly drop body runes. Level 2 goblins in Lumbridge drop water runes. Lesser demons drop fire runes: one trip can get you almost about 150 fire runes). Moss giants will drop the occasional 17 earth runes.For more info check out the RuneScape wikia.
No they do not drop dragon scimatars because even a rune scimitar is considered a rare drop from a cockarach monster and dragon scimitars are "MEMBERS ONLY" item.
The level 83 cockroach soldiers drop them on occasions in runescape, for nonmembers and members.
They can ask, but don't drop it.
I do not know the complete list however, I do know that these monsters do drop law runes: barbarians dark wizards wizards cockroach soldiers
They drop is after about 15-25 cockroaches. Don't be sad though. They also drop rune square shields and a huge amount of Mithril ore (in paper). (this is in f2p) (i don't know in p2p)