The letter 's' is one of the most common consonants in English that I haven't guessed yet. It frequently appears at the beginning and end of words. There are several common 6-letter words with 'e' in the third position that contain 's', such as "person" (though 'r' has been guessed and isn't in the word), "design", "beside", etc. Given my limited remaining guesses, 's' offers a good probability of success.