This is a difficult choice! But I would choose Cristiano Ronaldo
Why would you choose Ronaldo over Messi? Can you elaborate?
Easily Ronaldo. Consistent success along with performing at the top as he ages.
There is no doubt Ronaldo did have super success with Real Madrid winning 4 European Champion League titles but consistency applies to both him and Messi.
Ronaldo proved himself as a great player in the English Premier League with Manchester United, the EPL is the best and most competitive football league in the world. He then had super success at Real Madrid and now he is having success at Juventus too so he enjoyed success in England, Spain and Italy whereas Messi has not proved himself outside of a Barcelona team or the Spanish La Liga (league).