My desktop is 2010 vintage 6-core Phenom II 1100T with 16GB RAM, the motherboard is officially maxed out, but I've been told it can take 32GB just fine. It has been upgraded with an SSD and more recently a Radeon RX560, and it really does everything I need. Newer games do need lower settings, but it'll motor through most games at 720p. I added a PCIe USB-C interface card, so I'm not even stuck at USB 2.0 anymore.

I have considered replacing it with something smaller, now that all of my files are on a NAS and I don't need room for 5-6 drives in this machine. But I just don't feel like I would be getting enough of an improvement over what I already have, even with hefty new parts.

My laptop is a 2011 vintage X220i, and that is starting to feel a little bit behind, mostly thanks to the i3 inside. But it connects to 5GHz WiFi and is fast enough for browsing and video playback, so for now it keeps on truckin'.

Actually the best upgrade would be a decently powerful 12-14" laptop paired with an eGPU dock. That setup would handily replace both machines, but eGPUs just aren't a mature configuration yet, especially combined with Linux. Maybe in a few years.