For those running Sitecore PaaS, you should consider using Solr (and SolrCloud in Production) as Azure Search has some significant limitations.
For Sitecore XM and XP, you may be able to get by with Azure Search… but given the field limits, it can quickly paint your Sitecore environment into a corner.
For XC (aka, Sitecore Commerce) Azure Search should be considered a non starter as the field limits (1000 fields) can crush your implementations.
Beyond the field limits, there are several other Azure Search challenges that can severely impact your capabilities:
- Regular expressions spanning multiple items will return 0 results (SC 8.2.7 and 9.0.1 or earlier)
- Facet value calculation based on individual terms and not on the complete field value (SC 8.2.7 and 9.0.1 or earlier)
- Challenges with substring searches (SC 8.2.7 and 9.0.1 or earlier)
- Wildcard() field interpretation
- Fuzzy query patterns and parameters
- Join queries
- No Media indexing
- Range query limitations
- Mixing same name across types
Full details can be found here, but as you can see from above, choosing Solr is a much more prudent path: https://doc.sitecore.com/developers/90/platform-administration-and-architecture/en/sitecore-azure-search-overview.html