If football was judged by level of aesthetics, you'd be right.
Messi has failed to deliver in the bigger CL games many many times. In fact, one can make a good argument that he's never won it without playing in the best team in the world.
I agree with your second claim, Messi has never won the Champions League without being part of the best team in the world. And this proves what exactly? Titles are a team achievement, they are dependent on multiple players and other factors. Messi was the main driving force in 3 of those 4 but he didn't win them alone. In other words, this is completely irrelevant when discussing who the best player is, Messi could have 0 CL titles and still be the tournament's best ever player if his performance level remained the same.
As for the first claim, it's hard to challenge you on it because it's so vague and unsubstantiated. What do you even mean by "delivering"? Barca have been destroyed in the Champions League by large margins in recent years by teams that completely outplayed them, are those examples of Messi "not delivering"? Against Liverpool last season for example, I don't think anyone reasonable would disagree that Messi had a fantastic performance, scoring twice, setting up a huge amount of chances that his teammates fluffed... does that count as "not delivering" because the team lost? Do pinpoint those matches/ties where Messi's poor performance was the cause of Barcelona's defeat. It seems like you're reducing this to "Team won - delivered", "Team lost - not delivered", an impossible standard according to which pretty much every player ever is a consistent bottler.
Surely no one will take your seriously saying something like this? If you meant to say “La Liga”, no one will disagree. But CL? Come on, don’t be ridiculous. It’s not only about goalscoring, he also has less assist, less trophies, and less influential in knockout stages. He is less in nearly everything.
Besides, he only won Barca 3 CL (the other one was won by Ronaldinho/Eto’o, Messi was sitting on bench watching all of the knockout stages). How is he the best ever in CL history and its not even close?
I meant Champions League. Since you mentioned less goals and less assists, I assume the player you're suggesting as the CL GOAT is Cristiano Ronaldo.
I don't particularly care for any of those stats. I won't even go into "only won Barca 3 trophies" since that's completely narrative driven, players don't win CL titles, teams do. How high is Gento in your CL GOAT rankings? Goals and assists are at least an individual measure, though a very rudimentary one and one that doesn't even close to capturing the totality of a player's impact on a football match. Still, Messi comes out ahead in both those stats if you adjust for matches played. In terms of raw production, Cristiano rivals or even surpasses Messi in the CL, but there's so much more to a player than that.
Messi has an extraordinary scoring record in the CL, but he's also the best dribbler and playmaker in the history of the competition. He would be the best player in CL history even if his raw production was merely decent/good instead of a complete outlier. Best CL scorer of all-time is a better discussion: Messi has the better scoring rate overall, but Ronaldo has it in the knockout stages and he's arguably the more dangerous scorer in tight matches against elite defenses due to the unprecedented level of threat he poses off the ball and on the air.
Best CL player, however, only becomes a discussion if we go with narratives over performances. Cristiano doesn't have anywhere near the all-around ability to make that a discussion. He's not capable of producing for instance the all-around dominant performances Messi produced in two finals against Manchester United. This would remain the case even if he had 10 CL titles to Messi's 0. If raw production stats and team level trophies are the key factors to determine the best players for you, I guess we're simply too far apart in how we view football for any discussion to be productive.
I believe it's not close because no player's performances are in the same ballpark of consistent (10+ years) excellence as Messi's in this tournament.