Mondays, Wednesdays, Fridays. Heck, might as well add Tuesdays and Thursdays to the mix. 
Best
Available April 3: S&P 500 and E-mini S&P 500 Monday Weekly Options
S&P 500 and E-mini S&P 500 Monday Weekly options on futures will be available for trading beginning April 3. New Monday options will trade like existing Wednesday and Friday Weekly Index options, but they will expire on Mondays.