I'm pretty particular about random things.

I've got my desktop which lives next to my desk, and a single homeserver.

The server is in a Fractal Designs Define R5. Fits a full size ATX motherboard and 8x3.5'' hard drives.

I've decided that the case is my hard limit on sizing. My whole homelab (excluding networking) has to fit in that. Need more storage space? Upgrade the hard drives. Need it to be faster? Buy a better CPU.
This keeps my footprint down, allows me to move it around, and is relatively easy to work with using standard easily obtainable parts. Core count, RAM, and storage are all relatively cheap at this point.

But, with that in mind, it's running an older quad core AMD A10 APU with 16GB of memory and CentOS 7 as an OS. Plenty for running a whole bunch of docker containers (12 or 15?) and a couple of VMs.
It currently has about 31TB of usable (redundant) storage, an NVME for the OS, and a GPU for media encoding/decoding.

Is it the fastest? No. Does it have the most storage? No. Does it do everything I want it to do and then some? Absolutely.
In theory, 8 bays has a (current) maximum storage of 112TB so plenty of room to grow.

It is due for an upgrade because the CPU is starting to show it's age, but there are very few things I feel 'limited' about with this setup.
The ATX form factor also means as my personal desktop ages out, I can swap parts out and put them in the homelab.

Networking-wise, I've got a Dell 9010 with a quad port Intel NIC running pfsense as my router and an older Netgear R7000 acting as my access point (also due for an upgrade).

Between a standard/server desktop and the SFF 9010, that covers so many things.