Tier 1 (just need a basic site): Use the built-in website builders from their domain provider or hosted static site generators, like GoDaddy, Github Pages, etc.
Tier 2 (need plugins or ecommerce): If they require some more functionality like email lists or selling products then use services like Wordpress, Squarespace, or Shopify to build their site.
Tier 3 (extra data complexity): For sites that have more structured data that is not satisfied with tier 2, then use something like Webflow or Framer. These allow you to add more data types and categories to build unique pages.
Tier 4 (custom app) If they are building something unique that is complicated to build with the previous tiers, then my preferred stack to use is Django, Django Rest Framework, HTMX, Tailwind. Django-cms or Wagtail are also proven CMS to help build their site.
You should also consider serverless apps like Google Cloud Run or AWS Fargate so you don't worry too much about the infrastructure unless it is absolutely necessary to roll your own.
Tier 5 (a little bit of everything): Combine tiers with subdomains. For example, build their blog or marketing site on webflow, but have a custom API or an authenticated interface with a Django/DRF backend.
Ultimately, you need to see what level of technology your client is comfortable with and how you want to leave the project as your contract ends. Don't try to build a overtly complicated system that will give you more headaches later when the client calls on you again.