What I've learned in my limited time in the hobby is the hardscape is the backbone but equally it depends on the plants too. How many people, like me, spend ages getting the perfect angle on each rock only for the tank to go in and mask that perfection and more so completely hide it once they've grown in. So I'd say have a think too about how you envisage the end result
In answer to your question though, 1 if it's going to be heavy planted. 3 if you're likely to see a lot of the rock once plants have grown in, particularly if you can still see the dark cave like point in 3