I voted by most representation. So, between work and home, there's ext3, reiserfs, zfs, reiserfs, ext4, and NTFS. The two reiser boxes were built before he was found guilty and have had no problems FS wise--they are also the two home machines that get the most use. One is a file server with LVM2 and fakeraid and the other is my desktop, again LVM2 and fakeraid. There might be more ZFS in the near future because the ext3/reiserfs machines are on Ubuntu 12.04 and I don't like the performance of 14.04 on my laptop (fresh install w/ ext4). So, when I get around nuking and paving my laptop with FreeBSD and perhaps if I get bold enough to attempt ZFS on 32-bit machines, ZFS will be the filesystem of my choice.
I'm still not sure what to do with the 12.04 LTS desktop when support stops. It runs great now, with a good number of games working under wine. Reinstalling everything under another OS will be a pain. Because of systemd, it won't pass the Hairyfeet challenge to get to 16.04 and I'm not emotionally ready for systemd or bsd on it. Worst yet, I don't have time to be a system admin to facilitate and tune a change nor the time to backport updates myself.
I used ReiserFS v3 for a long time. Tried 4 for a while. But that's all been over 10 years ago. Thought btrfs is to be all the things originally planned for Reiser4, plus more so that there's no longer any reason to use Reiser at all.
If it's an old laptop, just leave it alone. I still have my first nettop computer that came with Windows 98. It still works, but it is so slow and limited on memory it is useless for newer software. Chuck the old one into storage, buy a new, more powerful laptop and pave that one over instead.
Doing zfs on 32bit is bad news. If your cpu is 32bit only you're better of with UFS on FreeBSD (also because it's likely single core only). Ram isn't quite the issue many make it out to be with zfs. I've run 3Gb fine, and 2Gb is pretty doable too with tuning assuming you're not doing anything intense with on the drive.
I'd do a "do_release_upgrade" to 14.04LTS and leave it there for now.. You've got two more years on 14.04 to figure out where you're going, Linux-wise.. I'm staying on 14.04 till close to EOL to see what my options are for a non-systemd distro, as I've tried 16.04 and I aint going there...Probably back to my "Linux_roots", that being Slackware...
I'm still not sure what to do with the 12.04 LTS desktop when support stops.
Given your username I would suggest VMS with Files-11.