Yeah CV through conquest is probably the fastest (map dependent though I guess). But on the other hand its only purpose is for HoF games (or GotM) since... it's basically just a domination win in reality with a twist to get it accredited by the submission robot. Not really in my own taste.
I totally understand. The mod I'm making is partly designed to make the game function "the way it was intended" by removing some of these shortcuts/exploits/bugs/imbalances.
But, there are two flavors of CV through conquest on Deity. One is the "liberate then GM-Bomb" which is arguably an exploit. The second is "capture great works through conquest" which is IMHO totally valid because of the way Deity currently functions. And it is arguably faster, or at least competitive with, pure peaceful cultural victory. And, I personally don't find it *that* exploitative... I mean, aside from the fact that it's easier than it should be. After all, culture through conquest is incredibly accurate, historically speaking. It doesn't feel at all inappropriate.
Deity is fundamentally flawed because the AI has tremendous advantages which can all be turned into player advantages:
* The AI techs faster? That just makes your trade routes more valuable, and stealing tech more profitable!
* The AI spits out manufactories, wonders, great works? They all become yours when their hapless military falls to a handful of units!
* The AI has lower maintenance cost, lower rush-buy cost and improves resources faster? That's money you can trade for that they won't bother to spend!
* The AI has more cities and population because they can grow and expand faster? Those cities just become yours!
* The AI has a high tech rate? The better for your RAs!
So, the punchline is: Deity is broken because AI "advantages" can be exploited to the point where "harder" flips to "easier".
But, in that context, warlike CV is probably always the best approach unless your civ's Uniques are better-suited towards peaceful play. /shrug
And yes, you can demand anything. Whether they give it has a lot to do with how scared they are.