Creatine vs Caffeine
for strength
Stronger evidence: Creatine
Stronger effect: tie
Safety: Caffeine carries a minor interaction; Creatine has none recorded.
For strength, Creatine has the stronger evidence grade.
Creatine
grade A high certainty
reliable improvement in strength/power with resistance training
3–5 g/day, training adults
Caffeine
grade B high certainty
reliable ergogenic effect on power and endurance performance
3–6 mg/kg pre-exercise, exercising adults
sources: PMID:00000003 · PMID:20000114