Short answer: cereals made from whole grains with little or no added sugar, high fiber (≥3–5 g per serving), and moderate sodium are the healthiest choices. Plain oats (steel‑cut or rolled) are one of the best options.

How to pick a healthy cereal (simple rules)

• Whole grain as the first ingredient (e.g., whole oats, whole wheat, whole grain corn).
• Sugar ≤ 6–8 g per serving (ideally ≤4 g for very healthy choice).
• Fiber ≥ 3–5 g per serving (more helps with satiety and blood‑sugar control).
• Protein ≥ 3–6 g helps keep you full (or add milk/Greek yogurt/nuts).
• Low sodium (look for <200 mg per serving).
• Short ingredient list, no artificial colors/flavors if you prefer.

Healthy cereal examples (categories)

• Oats: steel‑cut or old‑fashioned rolled oats (plain).
• Shredded 100% whole wheat or wheat biscuits (e.g., plain Shredded Wheat).
• Bran cereals: wheat bran or All‑Bran–style (watch added sugar).
• Whole‑grain hot cereals: barley, millet, or quinoa flakes.
• Low‑sugar granolas made from whole oats/nuts (check portion size).
• Sprouted‑grain cereals (e.g., sprouted whole grain flakes/loaves) and unsweetened puffed whole grains.

What to avoid

• Kid‑style “frosted” or chocolate cereals high in sugar.
• Cereals where sugar is one of the top 3 ingredients.
• Large serving sizes that hide high sugar/calories per bowl.

Serving tips to make cereal healthier

• Measure portions (many boxes list a small serving).
• Add protein: milk, soy milk, Greek yogurt, or a tablespoon of nut butter.
• Add fiber/phytonutrients: fresh or frozen berries, banana slices, or chia/flaxseed.
• Limit dried fruit and sweetened add‑ins (they increase sugar/calories).

Quick practical filter: choose cereals where the first ingredient is a whole grain, sugar per serving is low (≤6–8 g), and fiber is ≥3 g. If you want, tell me whether you prefer hot vs cold cereal, gluten‑free, or lower carb and I’ll suggest specific brand/product examples.