Short answer: Independent measurements published most recently show Dialog as the fastest mobile operator in Sri Lanka. Opensignal’s Sri Lanka report (published Feb 2025, measuring Oct 1–Dec 29, 2024) gives Dialog the highest Download Speed Experience (≈19.5 Mbps) and the strongest 5G trial performance. (opensignal.com)

Context and caveats:

• Opensignal (Feb 2025) — Dialog tops download- and 5G-related metrics in its dataset; Airtel, SLT‑Mobitel and Hutch score lower on Download Speed Experience. (Opensignal’s data period: Oct 1–Dec 29, 2024.) (opensignal.com)
• Ookla / Speedtest and other measurement vendors sometimes report different winners depending on the time window and metric: SLT‑Mobitel has been named the fastest 4G network in some Ookla reports (H1 2024), while nPerf and other aggregators have at times shown Mobitel or SLT‑Mobitel leading for other periods/metrics. That means vendor, timeframe and whether you look at median speed, “download experience”, 5G trials, or coverage all matter. (mobitel.lk, blog.nperf.com)
• Third‑party aggregator websites that pool user tests may show slightly different rankings (Mobitel or SLT‑Mobitel leading in some quarters). Use these differences to understand the uncertainty rather than as a contradiction. (speedgeo.net, bpvltr255.bpb255.workers.dev)

Practical takeaway: For general mobile data speed and overall experience, Dialog is the top-ranked operator in the latest independent Opensignal report (Feb 2025). If you care about a specific city or route, check recent local speed-test results and operators’ coverage maps (or run the Speedtest / Opensignal apps at the locations you’ll use) because actual speeds vary by location, device and time. If you want, I can pull up the latest coverage maps or compare Dialog vs. SLT‑Mobitel vs. Mobitel for a particular city/area.