The above was in reference to an AUR package that was called tor-git but the current one is abandoned and points to a dead git link.
The correct way to install tor is to trust torproject directly.
https://www.torproject.org/download/tor/
This has no systemd dependency. It is just pure tor as it comes from the source.
https://www.torproject.org/download for the browser which includes tor
There is also alpha links for the next generation tor which for the past decade haven't had any problems.
Make sure you download the sig file and test the archive before you use it.
You uncompress and extract the archive in /tmp or some place safe, you cd into tor.3...xxx run the configure file then make install as root.
You should also learn to configure /etc/torrc and study how to run this safely. I create a special user, nologin, no groups, and run tor as daemon with that user who has no wheel or other rights to the system. You use it, and then exit.
It is not a good idea to leave tor running when it is not directly in use. Tor emphasizes to learn to use it correctly otherwise you might as well not use it at all. So if you run it as a 66 service it is better you make a tree for it and enable/disable the tree separately from other services that run all the time.
It is also good practice to visit often the site and be alert of new versions, it is most often very crucial you update immidiately and not use an older version of tor. Don't expect arch or obarun to do this for you.
My 2c