Since it's the level of the humanoid that affects the type of cloth dropped (Usually), Deadmines would probably be best since it is like 95% humanoids. (There are a few parrots)
Lvl 1-12 mobs : linen
Lvl 12-24 mobs : wool
Lvl 24-36 mobs : silk
Lvl 36-48 mobs : mageweave
Lvl 48-60 mobs : runecloth
Lvl 45+ demons : felcloth
It's not 100% accurate, but gives you a pretty good estimate of what level mobs will drop what.
Edited, Jul 29th 2006 at 1:38pm EDT by Kleptomaniac