Heliod is a terrific God card that is going straight into Standard white life gain decks alongside Ajani Pridemate and Ajani, Strength of the Pride.
Of course, there is also an infamous infinite damage combo with Walking Ballista in Modern and Pioneer, but there is a big chance that it may get banned. Wizards of the Coast really don't like when these kinds of combos lift off.
With all that said, the main market for Heliod will be the EDH format. Heliod is a perfect commander and may get all the attention it deserves from the EDH crowd.