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.
Jefit in short
A large exercise library (1,400+) with a free logging tier. The downside: the Watch app, advanced analytics and ad-free use are Elite only, and $12.99 a month is high.
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).
Jefit free tier: basic: free and custom routines, 1,400+ exercises, logging and history, community. Paid: elite: $12.99/mo or $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 Jefit
Moving your data. Strong: Exports CSV; no import found. Jefit: Claims CSV export in its own blog; import not verified.
Watch support. Strong: Apple Watch (watchOS 10+); no Wear OS app mentioned. Jefit: Apple Watch (Elite only).
Ads. Strong: Not verified. Jefit: Elite is ad-free, which implies ads on Basic.
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.