I'm examining FreeFileSync after using Unison file sync (https://www.cis.upenn.edu/~bcpierce/unison/) for many years. Unison is quite a smart application and I never had problems with it, but it's development is actually stalled for many years and it lacks some new features.
It's fully a matter of taste but I find Unison's default compare view a bit more clear for the user because it shows extended paths only for folder or the first file of folder, and all other files in the same folder are just tabbed by several spaces and do not contain paths. So looking at the first entry of the group which is either extended folder path or path of the first file in folder we can easily identify location. And at the same time all other files in the same folder do not contain paths at all (no excessive garbage text), but are marked with tabulation to identify that they are from the same folder. It sound a bit complicated but it's really very convenient. Here is an example

When I play with FreeFileSync I find items only mode too short (I cannot easily identify the real path because I see only the folder name) and at the same time I think relative/full path mode is too excessive for files - sometimes their names are truncated because of long paths.
I do not ask you to simulate Unison of course, but I think that allowing separate view settings for folders and files at least for full path/relative path/item name option will make FreeFileSync much more flexible and customizable. For example Unison-like view may be easily setup in FreeFileSync: enable full or relative path for FOLDERS and at the same time item name only for FILES - and that's all.
Possible additional improvements that should be also mentioned (they are directly related):
- Tabulation for files based on their nesting level (1-2 spaces per tab level is quite enough).
- Collapsing or hiding files in folder if they all have the same status. For example, in Unison, if one folder is completely new (on some side) and it contains many new files inside it - Unison just show this folder as one item (marked as new on some side) and do no show all these new files at all - they are hidden because the whole folder is new and the sync action (either auto or manual) is assigned to the whole folder at once. It's just an example of such approach. Hiding may be replaced by collapsing/extending by user request. This prevents text garbage.
But the main proposal is just to separate folder / file settings, make them independent from each other.
Thanks!
Sergey