Linux

ZFS for nearly everything plus ZFSBootMenu EFI on root data pools. Get a bad upgrade? No problem, boot a previous snapshot (auto created with a pacman hook), which I had to do recently when 6.6.39 LTS kernel had a bug. Snapshots are also great when doing things such as upgrading postgres, hass, Plex, etc.

A combination of XFS and ZFS. I work in high performance computing (academic). While I love the reliability of ZFS for data archival and peace of mind that results provably haven’t suffered bitrot, sometimes I just need a 10 TB temp file(s) with fast mostly-sequential R/W. Appropriate selection of file systems lets me have both.

Ext4 bc of its speed for games and my main files. Btrfs on the root for compression

I use ext4 for all boot drives and root filesystems. Anything really important goes on a ZFS array. And for my Linux isos, I use a drive with ext4 + snapraid. The parity drive has xfs because ext4 has a 16tb file size limit.

Got rid of anything NTFS as it was unreliable and slow on Linux.

XFS on my server VMs and my laptops and desktops.

ZFS on my file server. I'd use it on my laptops and desktops too (and have done when I was using Xubuntu) but I've switched toFedora which doesn't come with a way to easily install with ZFS and I don't feel like jumping through hoops to get it done. And I can't stand btrfs. I don't know what it is about it, but I just don't like it.

Btrfs, ZFS and ext4. My servers use ZFS, my client machines mostly use btrfs and I have a sprinkling of ext4 partitions for specific workloads. I'm all in on CoW filesystems for snapshots, send receive, transparent compression and reflinks. I like btrfs on client machines and SBCs because it's easily available (baked into the kernel) and doesn't require maintaining dkms or holding kernel versions until ZFS supports them and because snapshot handling and other filesystem admin tasks are simple and straightforward. I run ZFS wherever data integrity is important, eg: storage servers and backup targets, but largely prefer working with btrfs.

It's all Ext4, but I run SnapRAID on top of that on my data drives. I'm sure lots of people would tell me I should use ZFS/BTRFS instead, but I'm used to SnapRAID, and I like the idea if something goes wrong, I won't lose all my data.

Defaults

So Btrfs, ZFS and ext4 (ext4 is virtual only)

I use bcachefs for my games, I like that it lets me have multiple disks with redundant data copies, plus ssd caching of frequently accessed files, this fs is linux specific for now as far as I know, and is still experimental. I use ext4 for everything else, and FAT32 for flash drives.

Btrfs main boot drive

Xfs main storage drive

exFAT external "archive" drive (easy to connect to Windows machines if ever I need my backup in someone else's windows machine in an emergency and such)

NTFS Usally for windows,ext4 for linux,btrfs to install linux on,vfat/fat32 for cross platform compatibility

I use Btrfs for my root partition to be able to rollback if something goes wrong after update. XFS: in all other cases, since I hate the lost+found directory on ext4. Although I don't think there's any significant difference between ext4 and xfs in performance and reliability.

We use btrfs for the / partition and xfs for any data partitions. Has served us well, the snapshot feature saves us some valuable time when an update goes awry.

I've been basically using btrfs on a lot of my disks because of the features it has.

Before I switched to a borg based system, my backups partition used btrfs for compression.

My main OS disk is btrfs so I can use timeshift snapshots, which are really worth checking out if you tinker with your system a lot.

I have two more btrfs partitions software raid0'd together for my steam library, nix store and other big but loosable things.

And my main home folder uses btrfs because I think the checksumming thing it does is more reliable for error detection, and cow is more fault tollerant on power failure?

... And I now fell like I'm one of those people with an over engineered storage solution. I just never get rid of old ssds or hard disks!

F2FS, because solid state and speed

Btrfs for the compression and snapshots

Servers - btrfs. Fewer layers of abstraction, easier to manipulate.

Laptops - ext4. I don't do anything weird with the onboard storage, plus it supports fscrypt.

Flash drives - exFAT. I usually need to access them on multiple platforms and exFAT is about as cross-platform as VFAT (but supports bigger files).

Depends. Slower desktop machines XFS.
Standard desktop XFS, if it has a smaller SSD, Btrfs.
Home server ext4/XFS + ZFS. Generic servers at work ext4/XFS, backup/storage servers ZFS.
Database server, experiment with ZFS with compression enabled - ratio 2:1, but encountered problems (probably a bad HBA model), standard ext4/XFS.
Hosts with virtualization, small server - XFS, big server - ZFS (technically a ZVOL).

ZFS for my server’s root pool and main storage pool. Ext4 with snapraid for my media pool. Currently btrfs on my desktop and ext4 under vanillaos on my laptop (not sure if I could partition it manually to use btrfs but I’m considering that for snapshots)

Whatever my installation CD had as default 😂. I'm guessing ext4?

Pretty much all ext4 except for a few Windows installs on NTFS.

ext4, but the btrfs activity visible in the kernel changelog has slowed down recently after a long period of many bug fixes, so maybe I'll give it a try next time.