Different startups have different needs based on where they are on their product-market fit journey. Pick one that you need the most right now.
Get a trained eye to tell you where your UX works and where it fails beat by beat. Get extensive notes and to-dos on UX fixes. Must be a product. No PowerPoints, please.
When have tons of customer feedback, but no clear sense of where to begin. Involves white boarding and review of all interactions and recommendations to improve flow
You're in the Valley of Tears. Your product is not dying but not getting better either. Involves revisiting user segments, product and feature bets and doing a product re-shape or re-set.