What you should have said is Footnote 4 = "Y" from that site.
Well if it were me I would pick up a used IvyCreek or Haswell board off that list.
It is old enough to have it in many developers hands but not too old.
Paired with a 3770T or Xeon E3-1265LV2 would be my choice. Using onboard graphics.
I like Gigabyte for desktops. Both of these use a server chipset and I like that.(EDIT:That site is wrong on this-NOT C216)
GA-B75M-D3H
GA-B75M-D3V
Both of these use Realtek LAN which is not good.
I dislike ASRock but their H81M-HDS board with Socket 1150/C216 is viable too.
Realtek LAN as well. Barf
OK after surveying every board that is LGA1155 almost all use Realtek LAN. That is not good on FreeBSD.
One except is:
ASUS MAXIMUS_IV_GENEZ-M
This one has Intel LAN but that "switchable graphics" sounds dodgy. Could be problems on FreeBSD. Unknown.
https://www.asus.com/ROG-Republic-Of-Gamers/MAXIMUS_IV_GENEZ/
when I look up these on Ebay they are real expensive for something so old (~$170USD)
Looks like Sandy Bridge so your talking 2012 Vintage. It uses a Core processor though.
I would not go any lower than Sandy Bridge LGA1155 and the 2500T for a CPU choice. Xeon 1260L or 1265L works too.
I am unfamiliar with AMD chips so I can't recommend anything there.
The reason I would use a cheap used board is I feel there is probably a good chance at bricking the board if you get it wrong.
Used board for cheap migrates that risk some.
You are looking at a highly risky maneuver putting this on an existing board.
I too love my APU2 and APU3 with coreboot. So anything that ships with coreboot is my answer for best new board.
Be advised things like Audio and Video may be crippled on coreboot. It is a work in progress.
The Purism machines are pretty nifty. They have been doing this a while now and have some variety.
https://puri.sm/products/
MinnowBoard3 is also a contender, Though not for performance but low power. So not what you are looking for.