I don't really see how these two assessments can coexist. As has being said, Ronaldo is exceptional at heading and at exploiting situations created by the team. No one currently playing is probably as good in those two departments, even though Bale is a fantastic header of the ball, too. However, Ronaldo can not dribble past people (he used to do that with speed) andcreate for himself. His free kicks are not even in the "bad" category, they are god fucking awful. So bad actually, that they have to be hurting the team. Real has had really competent set piece takers over the years, but I imagine any coach who'd take the fks away from Ronaldo would risk an ego-explosion of epic proportions and so one of the worst in the team at taking free kicks, continues to do so.
Two rather large weaknesses for "the best attacker ever". He also takes, for years now, by far the most shots of any player in Europe, meaning that while his goal scoaring record is really impressive, it is also due to the fact he is firing from all angles. His ratio has actually gotten better, but in his early Madrid years, it looked like this
La Liga 09/10
Shots taken: Ronaldo 7,3 Messi 4,7 Higuain 3,1
Goals scored: Ronaldo 26 Messi 34 Higuain 27
Shots taken: Ronaldo 6,9 Messi 5,1 Falcao 3,6
Goals scored: Ronaldo 34 Messi 46 Falcao 28
There are of course seasons, where the stats look more in his favour, but overall he takes a lot more chances to score than Messi and is probably closer relation-wise to other top attackers in Europe.
At this point we haven't even talked about other aspects of the game, dribbling past players, creating chances through passing and so on at which Messi is just miles better. I also don't understand the "he is more athletic" - argument.
Messi is much more agile, rides tackles like no one else and is - especially nowadays, where Ronaldo has lost a lot of his burst - not significantly slower. Ronaldo doesn't use his body to muscle past players or fend off defenders (he's a bit too divy for that), so the only benefit of his "body" is the heading ability, and we already covered that.
So while I agree that Ronaldo is a superb player (if you regularly score 30-40 goals, this is just a fact), I think he is far off from being the most complete attacker. The gulf between the two players mentioned has always been quite vast and it's only due to Real winning titles over Barcelona that he has won more than one Ballon d'Or.