My personal preference on brand would be Mercury, but genuine parts and dealer service charges are usually higher than OMC (Johnson and Evinrude). The reliablity of Johnson outboards is better than some cheaper name *cough* Tohatsu *cough* brands and parts are readily available. I have a 1972 4hp 2 stroke Johnson (found seized at the local landfill) put in 2 main crank bearings, added fuel, 3 pulls and it runs like a clock.
My advice would be to get the 9.9hp Johnson, just make sure you get the correct pitch propeller for the approx maximum combined mass of the boat, motor, passengers and gear (if any, not much room on a 2.7m blow up doll)