"Best" may be hard to find since the 775 socket is way obsolete. However, there are still a few new boards offered in that socket:http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100007627%20600007879&IsNodeId=1&name=LGA%20775
But you don't say whether you need an ATX, mATX, or ITX size board. So keep that in mind as you look through them.
You may have better luck buying used to find a really high-end board in that socket.
Browse here: http://www.ebay.com/sch/Motherboards-/1244/i.html?_dcat=1244&Socket%2520Type=LGA%2520775%252FSocket%2520T