The Cannondale is the best bike of those three, IMHO. The other two have pretty junky gearing on them (Microshift for the B'Twin, low end Shimano Tourney for the Scott). Shimano Claris on the Cannondale isn't the greatest, but it works well, and is uses the same style shifters (levers rather than thumb buttons) as higher end Shimano groups. The Cannondale is the best deal and the best bike I think.