It depends on what you mean by “best,” but for a web app with custom map styling and data overlays, the most common top choices are:

Best overall for custom styling + overlays

Mapbox Maps SDK / Mapbox GL JS

Best if you want:

• Highly customizable map styles
• Smooth vector maps
• Easy data overlays (GeoJSON, points, polygons, heatmaps, clustering, etc.)
• Great performance for interactive web maps

Why choose it:
Mapbox is usually the go-to for modern, fully styled web maps with rich overlays and a polished developer experience.

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Strong alternative if you want an open, flexible stack

MapLibre GL JS

Best if you want:

• Similar experience to Mapbox GL JS
• Open-source and more control over your stack
• Custom styles and overlays
• Lower vendor lock-in

Why choose it:
MapLibre is a good choice if you like Mapbox-style vector maps but want more openness and flexibility.

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Best if you need maximum familiarity and broad support

Google Maps Platform

Best if you want:

• Reliable maps and POI data
• Easier integration with other Google services
• Good overlays and styling options
• Strong geocoding, places, and directions ecosystem

Why choose it:
Great if you also need Google’s location services, but styling is generally less flexible than Mapbox/MapLibre for highly customized cartography.

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If your data overlays are the main focus

Leaflet

Best if you want:

• Simple maps
• Lots of plugins
• Easy raster tile + overlay workflows
• Lightweight development

Why choose it:
Excellent for simpler apps, but less ideal for advanced vector styling compared with Mapbox/MapLibre.

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Quick recommendation

If your priority is custom map styling + interactive overlays on the web, I’d usually recommend:

1. Mapbox GL JS — best all-around polished option
2. MapLibre GL JS — best open-source alternative
3. Google Maps Platform — best if you need Google’s ecosystem

If you want, I can also recommend the best API based on:

• your budget
• whether you need offline maps
• whether you want open-source
• your expected traffic
• whether you need routes/geocoding/places APIs