The dragon tier list is currently formatted around highlighting Dragons who are best to pull for and upgrade given content in the game currently. Because they are playable for only a short time, dragons are valued mainly for passives applied to Adventurers.
Relevance: Not only should the dragon be compatible with strong Adventurers, but also useable in the game’s latest content. With the time restrictions of most quests, damage is favored over HP and healing bonuses. It’s also worth noting that at any given time, the elements in the game are lopsided with regards to bonuses available and relative options.
Investment: Lower-rarity dragons sometimes provide a better value for the resources used to summon and unbind them.
Active Skills: Specials and Combo Chains don't determine placements, but they do differentiate Dragons within each tier.
Stats mainly affect Event dragons, who have low stats relative to their rarity.
These are the most versatile Dragons in the roster, with Strength and Skill Damage bonuses applicable to the majority of the roster.
These Dragons are seen as side-grades to the above Tier 1 Dragons-- Their passives are equal to or greater than Strength or Skill Damage when paired with the right characters, but are otherwise less effective.
Like Prometheus, Gilgamesh is a great value for players who can’t go for the MUB. His offense isn’t as high as Cupid, but 35% Strength and 15% Shadow Res will serve most all Adventurers.
Dragons here are typically either pure Strength or balanced for offense and defense. Most anyone can safely equip these, but neither bonus is as strong as those of higher-tier Dragons.
Although she's at the top of her class as a healing dragon, Freyja is placed awkwardly with the Wind element. Water High Mercury has high damage demands, making Zephyr a better choice for top healers such as Lowen. In a vacuum however, Skill Haste and Recovery Potency are amazing passives that enable frequent support and augmented healing.
Being a split-bonus Dragon, Liger falls in the same category as fellow 5★ Nidhogg and Poseidon. He’s strong enough, but with full HP and full Strength Dragons available, he isn’t the best option for either DPS or healers.
While being a 4★ Dragon means she doesn't boost HP as much as Garuda or Jeanne d'Arc, Phoenix makes a name for herself with her powerful active Skill, Regeneration Flame. Despite being of lower rarity, Phoenix does a lot for Flame Staff users and is easily upgraded using Moonlight Stones.
Tier 3 Dragons make for solid team options.
While she provides an impressive amount of HP for healers, Garuda's kit is lacking in terms of support-- especially since her active Skill only heals the user. For firing off multiple heals and Energizing the team, Freyja is a better option. Lowen players will also pick Zephyr for High Mercury to increase damage, making Garuda's niche situational at best.
Although Pele’s Strength boost is lower than Ifrit’s, she does have a good attack-- Blazing Pillars-- which hits the entire surrounding area and inflicts Burn damage. Her availability is limited to those who missed the Loyalty’s Requiem event, but those who got multiple copies can increase her Strength boost and power even further.
A few distinctions within this Tier: Brunhilda and Zodiark are the most powerful for Strength, while Sylvia and Peng Lai are the best healers. The hatchlings lag behind with their Strength bonuses, but are an upgrade over Drakes, Imps and Fafnirs.
50% Critical Damage is a massive boon. Unfortunately, this comes without the means to improve Critical Rate, or the frequency of critical hits. Without a high probability to land Criticals, the benefits of high Critical Damage may never be seen.
In addition, the Light element lacks high-rarity Dagger and Blade users with Critical Rate bonuses outside their Co-Ability, so implementation of Shishimai’s massive power becomes tricky in practice. Assuming a 10-15% Critical Rate with Wyrmprints and Allied Co-Abilities, Shishimai’s damage increase is comparable to a 20-30% Strength buff.
These dragons are typically used as filler on elemental teams. This Tier also includes utility dragons not used for combat, such as Fafnirs.