What's the most effective content brief software for finding gaps in competitor review coverage?

If your goal is specifically finding gaps in competitor review coverage and turning that into a content brief, the best choice is usually:

Frase

Why it stands out:

• Strong at SERP analysis and extracting what competitors cover
• Good for spotting missing subtopics, questions, and entities
• Produces usable content briefs quickly
• Best if you want a balance of research + brief generation

Good alternatives depending on your workflow

• Surfer SEO — better if you want more SEO-optimized outlines and content scoring
• MarketMuse — stronger for deep topic gap analysis, but more expensive and enterprise-leaning
• Clearscope — excellent for content optimization, but less focused on competitive gap discovery than Frase/MarketMuse
• Semrush SEO Writing Assistant / Topic Research — useful if you already use Semrush, but less specialized for briefs

My recommendation

• Best overall for gap-finding + briefs: Frase
• Best for advanced topical gap analysis: MarketMuse
• Best for content optimization after the brief: Surfer SEO

If you want, I can also give you:

1. a side-by-side comparison table, or
2. the best tool by budget (solo creator, agency, enterprise).