Intel usually has some stocks of boards for warranty replacement etc for 'some time' after a board goes EOL (but not for sale anymore - although some retailers may still have 'old stock' for sale).
As to which you should choose, It depends what you're wanting - whether its the absolute cheapest price possible (which you may get with a product nearing EOL status) or whether you want the latest and (usually) greatest - often with a price to match.... Just because a board is approaching EOL it will still have the full warranty if bought through official channels but if for some reason it needs to be returned for repair or replacement under warranty, if they've run out of stock for the EOL product, you may receive a different (but similarly capable) board as a replacement. More 'mature' products are also more likely to have had any issues ironed out of them than 'bleeding edge' gear but that said once EOL status is achieved, Intel usually won't provide updated drivers and BIOS files etc.
