M920q
You can get them stupid cheap, they have a pcie slot that will fit a full nic card, have a ton of 3d printed parts for them, and can take nvme drives. Plus run proxmox with ease. They're also the size of a small novel and are nice and quiet. I grabbed a used on on eBay for $100 tossed in ddr4 laptop ram I had laying around, got the cheap riser card and Intel nic for it. Runs opnsense and has been rock solid for months now. Totally worth it.