The best? That kinda leaves it wide open...
What features are you looking for?
Slot-1, socket, SCSI, IDE, on-board LAN, on-board video/sound? You kinda left it open.
Slot-1 boards i like the Asus P2B-D/DS and Tyan Tiger 100
Socket boards it all depends what you want on-board...LAN, SCSI, etc, etc.
840 boards if you don't mind buying new memory...
I refuse to buy another VIA single CPU board, i'll be d^&*$ if i'm going to touch a dual CPU VIA board.