We could also opt for Metal Casting from the oracle. It gives us early access to cheap forges (IND). Another decent alternative could be Civil Service, giving us early courthouses for REX, and very probably a holy city.
With our IND trait I dont think we can afford not to build the Oracle, even without marble.
Cheap Forges are especially nice with some Gold/Silver/Gems around since they provide extra happiness for them. And we know really well how hard the early happiness is to come by. Not a big fan of Colossus since there are like zillion other wonders we have to build so don't think MC is going to help there...
However, with no precious metals around, MC suddenly becomes far less attractive than the fancy economic techs like CoL and Currency (I can't think of a scenario where either of these would be useless).
Then there is Civil Service, which I think is just a wet dream fantasy

on higher difficulties providing you're not given double gold/gems.
Philo is a bit more realistic, though nowhere near as useful.
Aesthetics/Alpha are far more situational but can find their use under right circumstances (I remember that last game Alpha would have been a perfect tech to oracle).
So here are the specific cases for each tech:
Precious metals around => Oracle MC => Superforges
Lots of food and little commerce around => Oracle CoL => build Mids => rely on Rep-powered scientists
Crappy land => Oracle Currency => chop GLH ASAP => spam cities along the coast (+open borders with everyone on the continent and establish trade routes)
Stellar start (=2 precious gems in capital's BFC, cottagable land, some forests, some hills) => I would probably try CS slingshot
Marble in BFC => Oracle Aesthetics => tech Lit => chop out GL + National Epic ASAP => build Parthenon in many cities before actually building it for tons of failgold
Lots of jungle around, no strategic resources => Oracle Alpha => Steal IW
Good commerce start, Marble in BFC => Oracle Philo??? => use Pacifism + Caste while teching the Aesthetics line
And I totally agree that not building the Oracle would be pure stupidity....