Verdict
Aimchess is best for a dashboard of performance metrics; Mainline is best for actually drilling those weaknesses away.
Aimchess analyzes your games and gives you scores across categories (openings, tactics, endgames, etc.) plus some exercises. Mainline's difference is focus and follow-through: instead of six scores to interpret, you get one prioritized drill queue built from your real blunders, each priced in rating points, on a spaced-repetition schedule, so the diagnosis turns directly into fixed habits.