The comparison is very simple: one is t90, one is not. So for high-lvl pvm the choice is pretty clear. Like Elite said though, different situations may mean you have more choice but generally I'd just use the best tier you can. There's no argument that free fire runes is a valid reason to use camel over nox at telos, for example. I'd even say for those who can't afford t90 yet the stepping stone will be staff of darkness since it's way cheaper and the same as camel. That or wand of the cywir+vbook (cheaper still and better if you need the accuracy).