I decided to install Manjaro KDE alongside Windows 10 on my laptop, how should I proceed?
I mean, in the Installer there are 2 options that may fit my needs: the first one is “Install Alongside” (which should automatically shrink my Win10 partition to make a Manjaro one) and the other is “Manual Partitioning” (which is the one used by the majority of tutorials I’ve seen): which one should I choose? Is there a reason why most of tutorials opt for the latter?
Its just a matter of control … and honestly, competency.
If you want to read a bit and feel confident about partitioning things yourself … go for it.
But also … if you dont have a good reason to … letting the installer automatically cut things in half and just work might be the better option. And theres nothing wrong with that install.
Folks may have opinions about having a separate /home partition or whatever … and this can be useful for reinstalls … but again, if it doesnt matter to you, then its not important.
(PS - long time linux user … I just use / and SWAP … no fancy partitions … but thats me 
)
@mr.Y My modest experience is that, at first, check what kind of Win10 installation you have in place: MBR (Legacy) or GPT/(U)EFI and produce your Manjaro live USB in the same format. I would install it ‘alonside’ which also allows you to determine disk space sharing of the disk between Win10 and Manjaro. To my opinon, in case of mistake(s) while manual partitioning this ‘alongside’ way is safer and easier to repeat.
Please don’t forget in Win10 (before or after Manjaro installation) to disable Fast booting and tune the time settings accoding to https://mashtips.com/fix-linux-windows-dual-boot-clock-different-time/ .
It doesn’t really matter in the end - You should use the method you are most comfortable using.
When shrinking a Windoze NTFS partition is required to gain some space for Manjaro better do this with partitioning tools from within Windoze as this is more safe than doing it with any Linux tool. A defragmentation is also recommendable upfront.
Shrinking with GParted works usually but it could affect the file system in a way that Windoze will initiate a chkdsk afterwards, in worst case you can’t boot anymore.