Pleeeeease!

There's already a solution. Just don't check any of the sort options.
 
 

This is not a solution, because VST3 not sorted by default, and are installed in complete disorder.

Looks to me as though they are sorted alphabetically.

You didn't mention VST3 in your original post. Steinberg created the VST3 spec with plug-in subcategories. If you choose not to follow their protocol, then they will be categorized alphabetically.
 
You can go into SONAR's Plug-In Manager, create any FX setup you want, and save it as "My Default" or whatever. Then you can just call up "My Default" (it will be underneath the Sort by... options).

If you are looking for the old default behavior of
VST3 sort by category, VST2 sort by directory, DX sort by manufacturer,
it is gone. I miss it too along with nested folders. As mentioned above the only solution provided with the new plug-in management tools which will get close to the old "Default - All Plug-ins Sort VST3 by Category" option is a custom layout.

scook
it is gone. I miss it too along with nested folders. 

+1
Adding nested folders would make the new plug-in management system ideal IMHO.

I just get confused and I'm feeling quite clumsy.
I think that the new plug -in management is a big mistake from Cakewalk.

You can just ignore the new plug-in management options and continue using the Plug-In Manager. All the custom layouts I created previously, even those with subfolder within nested folders, open up just fine. 
 
I also did a test just to make sure you can still create custom layouts with sub-folders using the Plug-In Manager, and you can. 
 
After an initial period of disorientation I'm going with the new approach, but that may be because it's congruent with my workflow.

I have long use its own sorting method that suits me. To do resorting again I do not want. With that, a Sonar PluginManager does not work properly and allows a lot of mistakes.

Return sorting method Default All Plugins!

Pleeeeease!