Looker Studio: default
Free, Google-native, easy to share. Right choice for 80% of marketing dashboards. Starts well, ceiling is fine.
Tableau: analytics-heavy teams
Best for teams that need serious data modeling, blend multiple sources, or do exploratory analysis. Worth the license for dedicated analysts.
Power BI: Microsoft shops
Use it if you're a Microsoft-heavy org. Integrations are deep, licenses often already paid. Otherwise Looker is the right choice.