Best light for 2x2 SOG

Hello ,
I currently use a 400 and 600w HPS for my 2x2 flood/drain SOG , but my electric bill has been going up.
What is the most efficient light that will produce great buds and not use a lot of electricity?
I know the intake/outtake fans are using quite a bit of electricity. Any suggestions?
Thanks

250w produces 62.5ws/sqft so go with the 250wer as its in the good range.