My opinion on our strongest side would definitely include Cesc. Assuming all players are fit...
----------------Courtois
Azpi----Zouma----Terry----Alonso
--------Kante---------Fabregas
---------------Chalobah
Moses---------------------Hazard
----------------Costa
A midfield three featuring Fabregas, Chalobah and Kante would be amazing. Between them they have everything - strength, passing, tackling, creativity, speed, intercepting, endurance, intelligence and mobility.