Packages often enable the services they install right away.

That’s a problem of the package, not the package manager.

Generally this fits with Debian’s philosophy. But regardless I think it’s out-of-scope for why Apt is good. You could make a distro with Apt and not have your packages do this.

To temporarily install a package […]

I’m not talking about apt the CLI tool, but the actual package manager. The plain apt tool is only designed to be a convenience wrapper for common workflows implemented in other tools.

As you correctly pointed out, Apt has the distinction between packages installed as a dependency (“auto installed”) versus packages installed directly (“manually installed”). This is precisely one of the reasons why I consider Apt the best package manager. (Yes, I know other package managers can do this, not all though.)

If you want to install a package as manual, then later mark it as auto, you can do that with apt-mark.

dpkg-scanpackages is eternally slow.

Are you maintaining a PPA for others?

Frankly, I’ve never run into this problem.

The standard packaging tools […] are insane.

dh_make helps you create a package that adheres to Debian policy, and there is good reason for Debian to have those policies. But if you’re just packaging something yourself, you don’t have to use it. It’s just a template for new packages.

At the end of the day, all you really need to create a deb is to create two files debian/control and debian/rules. These are the equivalent to a PKGBUILD. The control file specifies all of the dependency metadata, and the rules file contains the install script.

The difference in packaging philosophy is that PKGBUILDs are external and they download the upstream sources. On the other hand, in Debian, they rehost the upstream package and add the debian directory. This means that building Debian packages is mostly hermetic: you don’t need access to the network.

What do you like about it?

Mostly that it makes super useful distinctions between concepts. But there are other goodies.

• Manually installed versus auto installed.
• Uninstalled versus purged.
• Upgrade versus Dist Upgrade.
• Dependency versus suggestion versus recommendation.
• The alternatives system.
• Pinning, and relatedly that packages can include version constraints in their dependencies.
• Interactive configuration at install time.
• Support for both source and binary packages.

I also do appreciate that Debian pre-configures packages to work together with the same set of conventions out of the box. But again, that’s a property of the packages, not of Apt.