From great mobile reliability to fast speeds, Chicago was the overall winner in best mobile performance among 125 U.S. cities, according to new report from RootMetrics. The Bellevue, Wash.-based mobile analytics firm used performance results from AT&T, Sprint, T-Mobile and Verizon to evaluate the results. In addition, Rockford, Illinois came in fourth with a weighted average of 96.8, behind Oklahoma City and Lansing, Mich., and topped the nationwide results in the speed rankings. Not only was…