General Power:
* "Pot of Greed": While banned in most formats, its ability to draw two cards is unmatched for consistency and resource management.
* "Dark Magician": A classic and iconic card, it's powerful in its own right and has numerous powerful support cards.
* "Blue-Eyes White Dragon": Another classic, it has immense attack power and numerous powerful support cards.
* "Chaos Emperor Dragon - Envoy of the End": An incredibly powerful monster with high attack, removal abilities, and the potential for infinite recursion.
* "Sangan": A versatile searcher that can bring out many powerful monsters.
Specific Archetypes:
* "Cyber Dragon": Known for its powerful effects, consistency, and ability to achieve high attack power.
* "Blackwing": Focuses on aerial swarming and powerful effects, often capable of overwhelming opponents.
* "Infernity": Powerful and versatile archetype with strong disruption and recovery mechanics.
* "Sky Striker": A powerful archetype with strong disruption and card advantage.
Powerful Spells/Traps:
* "Raigeki": A simple yet powerful spell that can wipe out an entire opponent's field.
* "Torrential Tribute": Powerful for disrupting large boards or removing threats.
* "Solemn Judgment": A versatile trap that can negate a powerful monster or spell.
* "Dimensional Barrier": A trap that can shut down an opponent's strategy by preventing summoning.
* "Mirror Force": A powerful trap that can destroy all attacking monsters.
Other Considerations:
* Link Monsters: While they don't have "strength" in the traditional sense, their ability to control the Extra Monster Zone and access powerful effects can be invaluable.
* Pendulum Monsters: Their ability to summon monsters from the Extra Deck and control the field can be extremely powerful.
Ultimately, the "strongest" card depends on the specific deck, strategy, and format. The best cards are those that best fit your strategy and can overcome your opponent's strengths.