I have not sailed a Celebrity but understand they are a reasonably fast, stable boat. Price is always a major factor and of course the condition of the boat. A couple of other things to think about… Are there any fleets for either model in your area? Both boats appear to have similar performance numbers although the Celebrity will probably be better in light air so I wouldn’t worry about the centerboard comparison. I’m thinking the Flying Scot will be the more comfortable boat to sail. Which is a consideration as you get older (trust me!) and if you plan on having guest crew who are not necessarily sailors. All this said, the best thing to do, if you can, is sail each one. See how you like it. At the end of the day, that’s really what matters.