Messi has been the top scorer in the champions league 3-4 seasons in a row, Ronaldo has come nowhere close despite generally facing worse teams every year.
He is a lot younger then Ronaldo and was constantly injured for his first few years at Barcelona, so has had a lot less time to develop then Ronaldo.
He is a big game player unlike Ronaldo who comes up with a goal and then is invisible for 80 minutes, he has played two really good teams this season Bayern and Barcelona he did barely anything. Messi was good against United three years ago and the best player on the pitch in last years Champions league final, best player on the pitch against Milan at least 2 times just this season.
I find it hard to believe that a player who has at times single handed outplayed Madrid,Milan, and the best team in said premier league wouldn't do the exact same thing to the likes of stoke.
The Xavi/Iniesta excuse isn't even valid anymore as this is his best season and both those players have been either injured a lot, or just not very good(Xavi) and have not played together that much.
He also makes more assists and is surrounded by a much worse team over the season, much better scoring record considering the amount of penalties Madrid get.
Amazing finish in the Everton game, still too little time for City.