MyFitnessPal in short
The calorie counter most people already know, with exercise logging on the free tier. The downside: barcode scanning, custom macro goals, ad-free use and CSV export are Premium only.
Cronometer in short
The free plan includes the barcode scanner and custom micronutrient targets. The downside: free reports and charts are limited to 7 days, and ad-free use, the fasting timer and the recipe importer need Gold.
Free tier and price
MyFitnessPal free tier: calorie, weight and exercise tracking, with ads. Paid: premium: EUR 49.99/yr or 9.99/mo on its site; the USD price was not verified.
Cronometer free tier: basic: food, exercise and biometrics logging, up to 84 nutrients, custom targets and a barcode scanner; reports limited to 7 days. Paid: gold: $10.99/mo or $59.99/yr.
Prices are the US App Store listings as of the check date, and some listings show several entries without labelling the billing period, so confirm in the store before paying.
Switching between MyFitnessPal and Cronometer
Moving your data. MyFitnessPal: CSV export, Premium only. Cronometer: Exports CSV; whether Gold is required was not verified.
Watch support. MyFitnessPal: Not verified. Cronometer: Not verified.
Ads. MyFitnessPal: Ads on the free tier; Premium is ad-free. Cronometer: Gold is marketed as ad-free.
If a game is what you are missing
Neither app has a game layer. We make GYM RPG, which logs the same sets, reps and weight and adds XP, a skill tree and a party boss. It is not a drop-in for either app, because we have no import tool and you would start fresh.