It is interesting to know what the most effective support heroes are depending on the player's rank. For low skill players (Herald, Guardian, Crusader) the most successful support heroes are Undying (57% win rate), Abaddon (56% win rate), and Crystal Maiden (56% win rate). Both Undying and Abaddon are very strong laners, making it easier for the players to dominate in early game. Winning early game is essential, especially in lower rank games. In a lot of cases, victory in the lane early game guarantees victory.
In intermediate ranks (Archon, Legend, and Ancient) the most successful support heroes are Warlock (57% win rate), Crystal Maiden again (56% win rate), and Abaddon (55% win rate). Warlock is a versatile hero, powerful on its lane, and having a huge potential to improve team fights. The intermediate rank bracket is dominated by support heroes that have good laning and early game potential but are also effective in team fights.
For the most advanced ranks (Divine and Immortal) the most successful support heroes are Warlock (56% win rate), Winter Wyvern (55%), and Jakiro (54%). These three heroes have one thing in common - aoe spells that give them an advantage in team fights.
Based on an article published on Gosu.ai, it becomes obvious that the most successful support heroes on average are those that have a high impact on early game and can dominate the lane. Winning early game is extremely important in lower-rank games while having aoe spells and being very aggressive in team fights are key aspects in higher-rank games.