None of them do what I want. And I'm not the only one.

Quite, which is why I've stayed with Opera v12 (v12.17 at the moment).

Daniel Aleksandersen, designer @Opera, wrote this:

It is a design decision based on the fact that everyone have enormous amounts of storage space available. You can clean up >your Downloads folder once in a while instead of having to decide between saving and opening files.
The old Open button in legacy Opera's Download dialog but files in a cache folder instead of the Downloads folder. This >confused the heck of many who could not find where their files were stored (because either option would store the >downloaded file on the system).
The new way is easier to use because the same thing always happen when you download a file. But some control of individual >files is taken away to achieve this.
It is a simplification of a regular task that did not need to be as complicated as it was.

Click on a file download link, let it download, and then double-click on it. Having an Open dialog would require us to have >a Save dialog too. This is not likely to change.

This just proves that the designers at Opera, like Daniel Aleksanderson, don't listen to how the real world users of the "proper" Opera use their product!

Why do we have to "clean up our Downloads folder once in a while" (actually I have a whole Downloads directory structure, not just a single folder) when with the proper version of Opera all temporarily downloaded files were deleted on exiting Opera. Which involves more, not less, user effort? The new Chropera of course!

And some more comments about this approach and that makes life easier for users with no experience!

No it doesn't (see comment above)!

It makes no sense! At least, make "open" an option! Or an extension / power user...
I want to open a Zip file, extract the content and Opera automatically delete the temporary file after closing! Same to flash updates, small programs, etc.

Exactly.

I don't want to download, open and then navigate to folder and delete the file!
Opera is dumbing down and limiting user choices...

Quite, so I'll be staying with Opera v12.xx for a while. It's been my default web browser for about 15 years, or more.