Short answer — the most recommended carriers for Colombo (CMB) → Dubai (DXB) are:

• Emirates — best overall for onboard comfort, multiple daily non‑stop flights, wide cabin options (First/Business/Premium Economy/Economy) and strong connectivity beyond Dubai. (emirates.com)

• flydubai — best value and frequency; several direct flights daily, modern 737 MAX service with a business-class option and often lower fares than full‑service Gulf carriers. Arrives/departs DXB Terminal 2. (flight.info)

• SriLankan Airlines — national carrier option with direct widebody A330 services on some rotations; good service and competitive prices (business-class lie‑flat on some flights). (flight.info)

• FitsAir — a Sri Lankan carrier that also operates direct CMB–DXB flights and can be cheaper on some dates (smaller operation, more basic product). (fitsair.com)

• Air Arabia (to Sharjah, SHJ) — often the cheapest choice but flies into Sharjah rather than Dubai; Sharjah is ~25–40 km / ~25–45 minutes drive from central Dubai (allow extra transfer time/cost). Use this only if price matters and you’re okay with ground transfer. (flightconnections.com)

Quick tips

• If you value seat comfort, lounge access and easiest transfers, pick Emirates or SriLankan in higher cabins. (emirates.com)
• For cheapest fares and many schedule choices, compare flydubai and Air Arabia (if you can land at/transfer from Sharjah). (flight.info)
• Always compare total price (fare + baggage, seat selection, transfer costs) on Google Flights / Skyscanner / airline sites before booking. (Schedules can change seasonally — check the airline’s official timetable for your travel dates.) (sa.wego.com)

If you want, tell me your travel dates and priorities (price, comfort, timing) and I can compare specific flights and fares for those dates.