There is no universal best stack. There is the stack your team can ship and maintain in eight weeks. For most marketplace and SaaS MVPs we reach for TypeScript end to end — Next.js or Remix on the web, Node or Nest on the API, Postgres for relational data, and a managed host you can scale without replatforming.
Mobile adds a fork: React Native or Flutter when native UX is core from day one; responsive web when speed to market matters more. We have shipped both. The wrong choice is building iOS and Android natively before you have paying users on either platform.
AI does not change the baseline. You still need auth, billing, and a database that outlives whichever model API is fashionable this quarter. Vector stores and LLM gateways plug in as services — not as replacements for core architecture.
We pick boring defaults, document them, and stay consistent through launch and post-launch retainers. Founders should optimize for velocity and hireability, not Hacker News points.