Rocks and hills are equally geographically limited.

Cranes would work, but I think you’re ignoring the massive difference in mass between what the biggest cranes in the world can lift and even the smallest reservoir.

some people are trying this:

https://qz.com/1355672/stacking-concrete-blocks-is-a-surpris...

I believe there's a beta test facility under construction now.

Still pretty small compared to pumped storage - they give a value of 20 megawatt-hours, the Cruachan pumped storage scheme (which isn't particularly large) stores 7.1 gigawatt hours:

https://en.wikipedia.org/wiki/Cruachan_Power_Station

For comparison, the liquid air battery in this article is rated at 250mWh.

I assume you meant Mwh? :-)

Are they efficient ?

Pumped hydro hits about 80% efficiency. So if you’ve got the right geography for it, it’s one of the best choices available.