How they compare
Both are part of Adult Time, so one membership includes them.
Modern-Day Sins built 160 long scenes between 2021 and 2025 around popular porn tropes and kinks, themed on the seven deadly sins, with well-known performers. It hasn't added anything since 2025.
Pure Taboo is known for story-driven scenes with real plots and acting, exploring taboo roleplay themes, and still adds new ones.