I've owned both the Samsung and acer currently have the Asus pg348q.
I can tell you initial impressions were good for the cf791 I wanted to like it but in the end I returned it.
Reason : no gsync + the cf791 seriously smears dark colours if your sensitive to this kind of thing it will bug you hence why I returned.
I haven't seen a smearing panel for 7 years the last panel I saw do this was the Sony x4500 and I returned that the next day , not something i expected to still be present on panels today.
The Acer though has serious Blb issues more so than Asus ± wonky bevels from poor build.
To be honest both screens have there issues, I find it's just a case of picking which defects you can live with.
This is a thread in overclock.net that me and another user posted pics video comparison and good / bad points. The panels compared are the Samsung and Asus but as the Asus uses the same panel as the Acer comparison is valid
http://www.overclock.net/t/1626558/help-asus-rog-pg348q-ips-vs-samsung-cf791-sva
Hope that helps