I am a current Allen and former Mckinney resident. From my perspective Allen is friendlier and more socially cohesive. Because the entire town plan was more based on keeping amenities centrally located and shared. 75 splits the town in half, but unlike Mckinney there is little stigma to living on the eastside or in one of the few non mc mansion homes on the westside. Allen is more comfortable in its skin and doesn't try as hard as Mckinney to get noticed. It's more of a hidden gem that is a 2nd move location after arriving in Collin County. You land in Mckinney, Frisco or Plano as default relo-villes. But, once your here you wish you would have started in Allen. Allen really has grown up to still feel like a small town that you can live happily in cradle to grave. Allen is more evenly highly educated and ethnically diverse community that interacts across lines. Mckinney is more defined by the location, income and the subdivision you belong to.