EOS is just Vanilla Arch with a nice installer… since you have used Manjaro, you shouldn’t have any problems. EOS comes with pamac still, I think, which is great for managing yay, though I prefer to do system updates using the command line. Just boot it up from a live CD and try it… unlike vanilla Arch, it is something, you can do with EOS… 
Here are some more details:
I used Manjaro for some years, after moving away from openSUSE. I used to like it a lot, but as you have found out yourself, it has become a bit of a pain… eventually updates would break it… either it wouldn’t boot, or other stuff would break, so I moved away from it to EndeavourOS, as I didn’t want to leave Arch per se.
EndeavourOS is easy to install, as it uses Calamares, like Manjaro does, I think. And it gives you the original Arch experience, as it uses the Arch repos and all. It does come however pre-setup, with all you need and some handy scripts, you can run with a single click.
The only major difference, from what I know is, that EndeavourOS uses Dracut instead of mkinitcpio and systemd instead of grub by default. However, during the installation of Arch and also using archinstall, you can set Arch up to use Dracut and systemd as well. I am running native Arch right now, using systemd but mkinitcpio, due to some problems and downsides of Dracut, I personally don’t like… however, for most use cases, this can be ignored.
Now, I decided to run native Arch, simply for two reasons… first, I wanted to go through the challenge of installing it and the other reason was, that Arch allows a lot of configuration and personalization. You get a lot more control of how your final system looks and how it works. However, after the system is up and running, there is not really any big difference compared to EOS.
That said, installing vanilla Arch, even using Arch install, still is quite complex, if you don’t know what you are doing. You still need to connect to the internet and set up some things through the command line and partitioning is a bit of a pain, even if you got some Linux experience. It is very well documented though and if you are willing to spend the time, it’s worth it. Otherwise use EndeavourOS and you get pretty much the same.
I love EOS and the EOS community is super cool and nice… I still put EOS on some systems, I set up and if my Arch system was going to break now, I would probably install EOS with KDE Plasma again, because I am not sure if I feel like going through the arch install again nor if it is worth it, since EOS does a great job with it.
So, I do recommend, to use either vanilla Arch or EOS, over using Manjaro. Some people have tried Garuda (Gaming Distro) and CachyOS seems to come up a lot these days as well. I don’t recommend Garuda, since it’s bloated and has quite a few bugs in it. I don’t know CachyOS, so I can’t say anything about it.
If you look for pure Arch, without the hassle of its installation and also look for a friendly community, go EndeavourOS. The Arch community can be quite difficult, though it has gotten a bit better. I love EOS, and I am still a lot here on the forums, much more than on the Arch ones… 
!. Here are my answers to your questions.
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