DonL: Thanks! I had already downloaded the XYplorer trial and looked through the help file but found no EXIF tagging solution. So I was about to give up on it. But this gives new hope!

BRU has four date metadata variables to work with: created, modified, accessed, taken. Will XYplorer's dateexif be equal to date taken?
The thumbnail mode in XYplorer is excellent. Very fast and configurable! Great with the right click popup previews. I think view mode "details with thumbnail#1" (where thumbnail#1 is set to pretty large) would be most useful since in the regular (non-detailed) thumbnail modes the filename is cut off which makes changes to the end of long filenames hard to see (
ellipsis, grr!)
Problem regarding tagging and putting tags in filenames: I've not yet found a very fast process in XYplorer for the type of filename tagging I need. It looks like there are two (or maybe three) alternatives:
A. set up rename commands that append a tag to filename (user > manage commands...). Select files and execute command through clicking user > rename > commandname or a set hotkey. But that might get slow/hard sometimes. Example: a folder of 100 images files where image subsets are to be tagged with multiple (different) tags from a set of 20 tags. 20 hotkeys is to much to remember. A repetitive three click menu process is too long. Things would speed up if the user commands could be put as a list (not menu) of text buttons directly on the toolbar AND if they somehow could be made into toggle commands (i.e. executing the command for tag "dog" on a file that already has "dog" in its name removes that tag from the filename). Advantages with A: the file name changes are immediate. No limit to the number of tags. Multiple tags can be added to each file (that is a must!).
B. set up Tags in Xyplorer by changing the default tag titles from "Red", "Yellow" and so on to whatever tags I need. Apply tags to selected files by adding the Tag dropdown to the toolbar and clicking Tag menu > tag. And then after tagging do an extra script to write tags to filenames. Drawbacks: each file can only have one such tag (?). For multiple tags I would need to (i) apply first tag for all files, (ii) write tags to file, (iii) apply second tag ... and so on. That seems to slow.
C. since XYplorer supports some form of scripting (I haven't looked into the details yet) AND dual pane mode, this might be possible: set up a folder with one script file per tag that when executes does a command like in A. Enable dual pane, let one pane view the script files then other the folder with images to tag. Select files to tag in one pane, the doubleclick a script in the other to apply tags.
Comments?
Edit: General brainstorming (not specifically regarding XYplorer): what I'm looking for seems to fall between two categories of common applications: Image managers are good at fast tagging of images but often presuppose that the user will also use the same application to later do tag based browsing/searching/viewing and so do not support complex file remaning based on a combination of datestamps and tags. File Renamers/Managers are excellent at complex file renaming but have obstacles for very quick multi-tagging and have no or limited thumbnail mode. So far I've mostly looked for File Renamers/Managers that can do the other part too. But maybe I should be looking from the other direction: some image manager that is excellent at tagging AND at least support some sort of database export (to XML, CSV or some other plaintext format). I could then make an AHK script that parses the export and for each path associated tags does a rename action.