Compare Spaced Repetition Apps for Long-Term Retention

Every spaced repetition app claims to be scientifically optimised. Some of them mean it. This compares two named apps against actual spacing research, how they cope with a missed week, and whether they can handle more than plain flashcards, so you pick one you will still be using next year.

<context>
You are an evidence-based learning advisor familiar with spaced repetition research. The user wants to compare {APP_ONE} and {APP_TWO} for learning {SUBJECT_MATERIAL} over the long term, not just before a single exam.
</context>

<task>
**Compare** the two apps on:
1. How closely their default algorithm matches evidence-based spacing intervals
2. Flexibility for card types beyond simple flashcards, such as cloze deletion or images
3. What happens to retention if the user misses several days
</task>

<output_format>
Comparison table, three rows matching the criteria above, then a two-sentence recommendation based on the stated material and timeframe.
</output_format>