Manjaro vs Arch

So I have been testing out the two in VMs the past few days, and I just succeeded in getting an arch install to gnome 3. I am wondering what anyone would say the disadvantages to going with a Manjaro install are. Basically what would you say are the killer advantages to the customization levels of Arch vs just rolling a quick Manjaro install. I am new to using Linux (about 3 days or so), so I would say I am not sure of what I like yet exactly, but the idea of jumping into configuring arch doesn't really bother me (basically I just went full fledged into building from the command line to learn the basics, and I feel I have a better grasp because of it). Naming from the time I was using Manjaro I really liked the additions like the software manager, and also the icon set/ themes (not to mention the quick and easy rolled driver support and config). Additionally I have some other questions. For one with Manjaro I seemed to have full support for native resolutions (2560 *1440) and 1080p on my two monitors, and it seemed faster 3d acceleration vs what I have now with a basic gnome 3 shell in Arch. I guess this is more of a Virtual Box question, but what would cause that? The device reported by the system is a Virtual Box graphics adapter, so would installing a proprietary (I have AMD 7950s) improve that to the level that it was in Manjaro? Also just general guide lines to tweaking Arch some more would be appreciated (I guess more in line of nice themes or killer apps/ gnome extensions you like). Also one more question, I now have a problem with the Manjaro VM in that when I go to start it it executes up to the point of starting X when the screen flickers (the VM window) and it hangs on " Reached target graphical interface. Reached target multi-user system" this seems to be a display driver issue, but how can it be fixed. I assume just loading the live iso into the editing on the command line would work, but where should I start with that issue? 

Both issues are VM issues on windows that you probably won't have if you use the proprietary microsoft virtualisation instead of oracle's. The linux kernel actually contains about 20.000 lines of code submitted by Microsoft in order to optimize the linux kernel for use in HyperV, microsoft's virtualization engine.

As to Manjaro vs Arch: Arch is a fully modular install, what you don't install manually, you don't have, so you won't have randr for instance, which is possibly also why you don't have all resolutions showing up, and you don't have proprietary graphics drivers from the official repos, because Arch is open source only, you have to pull in the non-free drivers from a separate repo, whereas Manjaro has all the non-free codecs and drivers and apps preinstalled. You can also get Manjaro with Gnome, it's a community release, or you can install gnome from the official repos after you've installed the official XFCE orOpenBox release. There is no linux distro that doesn't have all the common DE's in the repos, a DE is never typical to a distro or vice versa. There is a difference between Arch and Manjaro: primo, the official repos are not the same, Manjaro has it's own repos to avoid poisoned packages which may pop up in the Arch repos, because of the rolling release model, and that break stuff because with Arch, being leading edge is considered more important than guaranteeing that packages work without tweaks, because the tweaks will be well documented on the website, and it's an enthusiast distro, so for people that don't mind doing tweaks after updates, while Manjaro is based on Arch, but is also for noobs, so they want everything to be "pre-tweaked", and they will hold off pushing updates in their rolling releases until they have pretweaked what needs to be pretweaked for the users; secundo, Manjaro is not a lean and mean distro like Arch, Arch comes with nothing out of the box, you need to pull in everything that you need so that your system is as lean as possible, which translates in Arch with XFCE using almost 60 MB less RAM than Manjaro, so even while Manjaro is not a bloated install in comparison to say Ubuntu or another typically bloated distro, it's not as lean out of the box as Arch; tertio, Manjaro has a few user friendliness improvements, like graphical login screens, and a great full automatic hardware detection tool with driver management including non-free graphics drivers.

Also, Manjaro is not a port of Arch, it's more like a remix that's almost a port, like Mint linux is to Ubuntu let's say, rather than like Ubuntu is to Debian. So Manjaro is still Arch, just with a lot more features, which is exactly what Arch is trying to avoid, to provide a lot of features out of the box, because that would go in against the KISS philosophy. Generally, Manjaro can be considered as an intelligent recommended Arch install with user friendliness improvements and added service support. Manjaro is also still in beta, they're at version 0.8.7 now, which will be released officially this month. Manjaro is still using the 3.9.10 linux kernel for the moment, which is more recent than most distros, but Arch and Fedora are on 3.10 by now, which is still considered unstable by Manjaro, which is also effectively unstable in Arch for some things that need to be tweaked before they will work, and which is stable for Fedora because most maintainers in the linux foundation are in fact RedHat people, and Fedora prides itself in being the most bleeding edge distro (which is in fact just a business decision by RedHat, since Fedora is the community testbed for RHEL, so they want Fedora to be bleeding edge because they want to test new things as soon as possible before using them later in RHEL). Arch is just behind Fedora, not quite as bleeding edge, but at the forefront of leading edge, whereas Manjaro is still leading edge, but allows users to switch kernels on-the-go in a session, and will wait for tweaks and fixes to come out in Arch before implementing changes.

I find Manjaro to be really practical for people that want a low-maintenance Arch install and don't care about non-free packages and a tainted kernel. That would be mainly home users, because enterprise users will typically want to keep their kernel untainted, so they will prefer an Arch install if they want or need to use Arch, but they will hold off updates until they are community tested and all the fixes are known. Arch will also get the last drop of performance out of a system because it can be configured 100% custom to do that, whereas Manjaro is clearly orientated towards recent consumer platform hardware, with a lot of power management tweaks and optimalisations for typical home user PC's already built-in. Like there is no use in installing Manjaro is you want a server install, that would just pull in a lot of unused and unnecessary packages, even though Manjaro will perform great as a server too, but it's not the primary focus. Arch has no primary focus, you have to shape it yourself for the role and the hardware you intend it for. Also, KDE seems to take Arch into account, so KDE seems to work better on Arch than gnome, which often needs extra Arch community tweaks, whereas KDE mostly seems to be pretweaked for Arch by the KDE devs. XFCE in the form used by Manjaro out of the box, with plank and whisker and compositor active by default, uses about the same amount of RAM as KDE on Arch, which comes without trimmings out of the box, which also highlights the difference in philosophy between the two distros.

As to x crashing on Manjaro, there was a little bug at one time that made x crash at startup some time ago because of the way AMD non-free drivers have to be activated manually in Manjaro with one simple command. You can type "startx" at the prompt if your xserver doesn't start at boot, and it will correct automatically after doing the suggested software updates.