I would disagree there is little benefit to using lvm with a single disk, unless you only use it as a raid mechanism, which I don't. Otherwise, I tend to compartmentalize my os for root, var, var/log, home, usr, and others, but occasionally I need to grow them over time, even adding another disparate disk to the system. LVM lets me do this where I cannot with a base ext partition. Also filling a bare root ext partition tends to fsck up the os royally, sometimes fsck is help in recovering, or not. Never had this again switching to using lvm for everything.
Last time I built my laptop with arch, I was bent on using ZFS, but arch and maybe linux in general couldn't boot off an encrypted volume still. BTRFS not sure currently, but it always seems a bit sketchy anyways. Years later, I'd love to know if this works yet.
End of the day, I need 1) raid, 2) encryption, 3) volume management/scaling, and 4) ssd features to keep them alive. I use only samsung disks that tend to do their own auto-leveling as I have found other SSD's entirely unreliable when layering said requirements currently with mdraid/luks/lvm/ext. Samsung seems to nail it for longevity, though my laptop currently uses only a single toshiba m2 ssd and has been working fine for almost 5 years. Maybe *other* vendors have finally copied them, but I simply don't even consider non-samsung drives these days.
ZFS seems the long-term ideal to replace mdraid/luks/lvm/ext all in one, maybe BTRFS, but curious if anyone's figured it out yet. Probably wait for a new desktop/laptop to try this.
-mb