Based on what I've read, third base is the preferred seat for counters at a table with other players because it gives the counter a view of the cards on the entire table without having the move his head about suspicuously.
However, first base provides the same vantage point.
Now in the BJ I've played, I've felt pressure by the
dealer to place my bet before any cards are dealt. So it seems that by sitting at first base one can obtain the most accurate count at bet time (unless one can sit at third and place his bet just before receiving his cards -- which seems like a dead giveaway that he's counting). So why would third be better than first?