Mac peaked higher than both, period. He was legitimately one of the 5 best players in basketball at his peak (2000-05), this was never the case for Peak Melo (2008-13) or Peak Dame (2016-21)...
All three of these guys were known for scoring the ball more than any other trait, look at the peaks I defined above---->Mac was a superior scorer than both in regular season and postseason, with superior postseason efficiency to boot...
If you give an equivalent 8-year prime to all three, it goes 2000-08 Mac, 2005-13 Melo, 2013-21 Dame:
•McGrady's durability is underrated, he actually only had one year of his prime that he played fewer than 67 games, and he averaged 69.6 games played thru the duration if his prime. He did often seem to have these knick-knack injuries though, and more importantly it's hard for me to forgive a guy of his caliber playing essentially a full season and his team winning only 21 games during it ('04); it's also hard for me to forgive a guy missing the playoffs in The East during his prime in arguably the weakest conference and era ever...
We shyt on someone for winning "The Weak East" but here's a guy who couldn't win a playoff round in that "Weak East". It's without question a demerit...
You can count '06 as a lost season to injury, but it's really the only lost year of his prime, again Mac was a little more durable than we remember. Still, his teams only won 42.8 games/year in his prime, only 3 50-win seasons in 8 years, missed the playoffs entirely twice, and never won a playoff series. There's no way to not view this as a negative for Mac, there's no reason a guy of this immense talent should never have won a playoff series...
•Melo led his teams to 4 50-win seasons and an average of 48.4 wins/year while playing 71.1 games/year. His teams did make the playoffs every year of this defined prime in a strong West and that matters. They also lost in Rd1 6 of those years under Melo's hand and their deepest run was mostly because they had Chauncey, Melo otherwise never exhibited you could win at a high level with him as your best player consistently...
His conditioning was an issue, as was his willingness to play well with others and exert himself defensively. I think it matters that he never missed the playoffs, I just think it's balanced by the fact he wasn't really great when he got there...
•Dame is the wild card because it's still in play that he could keep extending his prime, which would change the evaluation since he already peaked in the same realm as Melo. As it is, Dame played in 77 games/year thru his prime, leading Portland to 47.4 wins/year in a pretty tough West most of that time...
Like Melo, Prime Dame never misses the postseason, he gets points for that. Like Melo, he also only got outta the Semis once, but since these are evaluations you sometimes have to sit hairs with, he made it beyond Rd1 three times, the most of these three players...
Losing 5x in Rd1 in an 8-year stretch isn't great, but it does matter that he advanced more often than the other two...
...........
I would probably rank Dame just slightly over Mac, even though again I think it's obvious Mac was the best of these three peak-for-peak. He just didn't win enough, even one deep playoff run changes where he historically lies because he did have a high peak. He didn't do it...
I think Dame proved to be the easiest of these three to build around, even as Portland didn't maximize optimum team-building, so this matters. I've pushed back against the notion of Dame as an All-Time clutch player but he WAS more clutch than these other two, so that matters. But it's a fine line, honestly Mac is right there with him and I'm not tripping on someone ranking him over Dame...
There's a little gap between Dame/Mac and Melo to me, Melo's career is romanticized, it wasn't really great. Notoriously tough to work with be it teammates, coaches or front office. Before Ben Simmons or James Harden existed, he was the OG player who was always questioned for loving celebrity more than commitment to the game of basketball. On the floor his game could be smooth to watch but in this group the results just aren't there to warrant exalting him as a higher category of player---->he isn't the best scorer in this group of three, he was only the biggest winner of the three marginally, wasn't the best floor-raiser of the three, had the lowest peak of the three relatively speaking, etc...
As I said, I was a T-Mac Stan in junior high who immediately turned Melo Stan and was there his entire Denver tenure, he was my favorite player. I have an appreciation for Dame but wouldn't consider myself a fan and definitely think there's narrative around him that overrated him some, but I try to pull emotion out of these conversations and look at it all objectively...
They all are probably three of the Top 75 players ever. Mac shoulda made it, but if you have to question any of the three's inclusion it should be Melo...