Pre-injury R9 (suffered his first very serious major knee injury at the age of 22 (recently turned 23 in fact) during the 1999-00 season, in fact Ronaldo already started to suffer from injuries during the 1998-1999 season aged 22 where he only managed to play in 28 games during that season coming off a 44 games and 30 goals season prior in what was back then the by far best league in the world) was better than Messi that age and better than anything that I have ever seen his age group. Mbappé is not even close. Laughable to compare them with each other in fact. It was amazing for me (born in the 1990's) to even have that discussion with users who supposedly saw both in their prime.
R9 was something else entirely. The nature of some of the golazos that he scored for us during the 1996-97 season is probably something that Mbappé will not come close to doing in his entire career. Yet to see him even score even one such goal to date (golazo).
Anyway I would still take Mbappé without a doubt but the ridiculous hype and comparisons are not doing him any favors and Pelé moulding him as some kind of successor (see his Twitter profile and some posts in the past and their exchanges) because he happened to score in a World Cup final and win it while being below 20 years of age.
Forgetting that Ronaldo won it as a 17 year old in 1994 (granted he did not play a minute but just speaks volume how good and talented he was to be included in such a stacked Brazil NT back then) and played much, much better in 1998 than Mbappé while only 12 months older. Failing "only" to win the final due to reasons that most football fans are already familiar with. Should never have played that final. 4 years later, as half-crippled and being out for almost 3 fucking years, he became the top scorer and won the World Cup again. Scoring twice in the final against a historical heavyweight like Germany (only second to Brazil in terms of honors alongside Italy).
Put some respect behind the real Ronaldo and arguably the first modern football superstar and a player that changed how we look at football and inspired Messi, C. Ronaldo and practically every megastar and elite player that followed after him including the very same Mbappé that happens to be 22 years younger. Talk about legacy. It is not all about stats or individual trophies otherwise the Inzaghi of the 1970's (Gerd Müller) would be rated much more highly than Cruyff but it is just the exact opposite for good reason.