I'm choosing 'a' because it's one of the most common vowels in English. Since the word is 8 letters long and has an 'e' at the end, there's a good chance it contains 'a'. Many common 8-letter words ending in 'e' (like "practice," "celebrate," "generate") contain the letter 'a'. Vowels are generally a good starting point in Hangman, and since 'e' has already been successfully guessed, 'a' is the next logical choice.