Short answer — best options for Colombo (CMB) → Dubai (DXB):

• Emirates — best overall for comfort, frequency, premium cabins and lounge access (arrives/operates from DXB Terminal 3). Great if you want more daily departures, business/first class, and wide connectivity onward from Dubai. (Emirates.com)

• SriLankan Airlines — full‑service carrier with competitive fares, Oneworld connections and a good onboard product; good choice if you prefer a national carrier and mileage credit with Oneworld partners. (eg.wego.com)

• Flydubai — low‑cost / value option with several daily non‑stops and good departure times; cheaper fares but fewer frills (pay for checked baggage/seat selection unless included). Flydubai services operate from DXB Terminal 2 (codeshare flights with Emirates exist). (flight.info)

• FitsAir — a smaller operator that also flies the route sometimes; can be useful if you find a cheap direct option but check schedules and reliability. (flightsfrom.com)

Quick facts and tips

• Typical non‑stop flight time: about 4.5–5 hours. (flightsfrom.com)
• Frequency: Emirates and Flydubai offer multiple daily flights; SriLankan typically 1–2 daily. (flightsfrom.com)
• Booking tip: compare total price (fare + baggage/seat fees) — low‑cost fares can look cheaper but add up once you add baggage.
• Loyalty & connectivity: choose Emirates if you want superior lounge/service and many onward connections from Dubai; choose SriLankan if you value Oneworld ties; choose Flydubai for the lowest fares/timing. (Emirates.com)

If you want, I can compare current prices, schedules and fastest/cheapest specific flights for your travel dates — tell me your dates and cabin preference and I’ll fetch live options.