Do note that this is more oriented towards Conquest but is slightly biased towards other modes as well. I'm only Silver IV in Conquest but I have a lot more experience in other modes (Clash specifically) so do be advised of that when looking at this list.
Also, this is made in consideration of the upcoming update, with all of its various buffs.
SS - Nerf immediately, is far too OP to have a place in the game in its current condition.
S+ - Top-tier pick for its specific role in the game, first 4 bans will usually be of these gods and first pick will usually be one of them, unless one of the SS' weren't banned.
S - Extremely high-tier picks, can almost always get away with using these in almost every single situation.
S- - More risk starts to come into play with these picks, but for the most part you'll do JUST fine with them if you're experienced enough with them.
A+ - Quite a bit of hard experience is needed to pick these and be successful with them in a professional scene, but they definitely aren't obsolete and can still be used.
A - Lots of risk behind picking these, in order to be successful with them in a professional scene, they have to be literally the single god you're the very best with. This is the point where gods shouldn't really even be considered for a pick in an actual professional scene, only do so if you're left with NO OTHER option.
A- - At this point, the risk begins to outweigh the reward when you make a pick from this tier. To say they're absolutely impossible to succeed with in ranked would be absurd, but it's certainly quite improbable.
B - These are the gods that would be considered truly average and balanced among all others, meaning they hold no extremely high amounts of power over other gods and thus shouldn't be played in a competitive setting.
C - Unbelievably underpowered gods, you shouldn't pick these by any means just because they hold absolutely no power over any god in a higher tier.
D - These are gods that are completely missing an extremely important component in their kit and thus are completely and utterly unplayable in any sort of competitive setting, regardless of the actual elo or ranking placement class.
S- - Izanami and Terra
A- - Camazotz