I like the 1st and 3rd boards :
1. CPU socket is way out in it's own corner. Would be good for an overkill heatsink fan combo (but might get in the way of hard disk placement if installed so).
2. For the 1st board - VLB slots for VLB cards - a hallmark for 486, but not required though. Would be a great board to install a Tseng ET4000 VLB card or one of those rare 3D Blaster VLBs for a kick. 😁
3. I myself am using a PCI based 486 similar to the 3rd one. Using a Virge DX card on it for both DOS and Windows 3.11.
4. The 1st board can accomodate very long cards without getting hindered by front panel/speaker/led pins and wires obstructing them, easily. Other boards might need adjustment of where to place long cards. But then again, there are only a few cards that are very long - LAPC-I, SBAWE32 (older, "full" models).
The 1st board requires a Floppy/HDD/I/O card though. The 3rd has everything ready.