Strong in short
A plain log with an Apple Watch app and a one-time Forever purchase. The downside: the free tier caps templates at 3, and we found no import from other apps.
Alpha Progression in short
Pro generates plans and recommends progression. The downside: the most expensive of these apps, and the plan automation is Pro only.
Free tier and price
Strong free tier: 3 workout templates and unlimited saved workouts. Paid: pro: $4.99/mo, $23.99 or $29.99/yr, Forever $79.99 or $99.99 (US App Store entries are inconsistent).
Alpha Progression free tier: unlimited logging, own plans, rest timer, records and CSV export. Paid: pro: about $12.99/mo or $79.99/yr on the US App Store (one listing showed $69.99/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 Strong and Alpha Progression
Moving your data. Strong: Exports CSV; no import found. Alpha Progression: CSV export is free; import not verified.
Watch support. Strong: Apple Watch (watchOS 10+); no Wear OS app mentioned. Alpha Progression: Not verified.
Ads. Strong: Not verified. Alpha Progression: Not verified.
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.