Authoring WinHelp files is a pain (and indeed better done by hand or via a convertor from a saner format), but from a user perspective WinHelp is IMO the best format - the only thing i'd like (assuming WinHelp was still distributed with Windows 10 - though you can copy it from a machine that has it and it'll work) is the contents sidebar from HTMLHelp (which is also nice, but a full blown browser engine is IMO overkill and it gets often abused with fancy CSS and javascript effects in some CHM files - WinHelp is too limited for that, though some programs did try to push things further than should be pushed).

Call me a very ancient oldie, but the - in my opinion - best help system ever was the one from VAX/VMS.

It was rather simple, but thanks to its hyrarchical structure extremely accessible, even when you just started using the operating system.

DEC's extraordinarilly well structured documentation added to the whole experience.

Compared to that most technical documentation today is outright atrocious.