I always recommend running an LTS kernel unless you have a reason not to. The main reasons not to would be:
You just like having and testing the absolute latest stuff
You have very new hardware which requires a more recent kernel
There is some new feature introduced that is must have for you
To install the LTS kernel you can use:
sudo pacman -S linux-lts linux-lts-headers
Mainline non-LTS kernels can sometimes introduce issues early in their lifecycle. They are typically fixed in later point releases. But they are very shortlived so about the time they get fully stable they are EOL.
And if you use akm (recommended, since you won’t have to do any grub reconfig yourself), when you choose linux-lts, also check linux-lts-headers with it.
I recently installed lts as a backup option but didn’t install the headers with it, and ended up with a useless blinking prompt and no graphical desktop. Installing the headers solved the issue. As I use nvidia, this was probably the reason?