I honestly just think GOAT debates that span across 7 different decades of football just don't make any sense. The only quantifiable way to rank one player against another is their individual achievements and honours, but that leaves you nowhere close to seeing the full story.
If you stuck 2011 CR7 in to 1960's football he'd seem superhuman in comparison to everyone he played against and no one would come close to him. But equally if Pele was born in the modern era, he'd be the beneficiary of years of advancements in sports science and medicine... but that still gives you no idea of their level in relation to eachother, it's just incomparable.
There's more ground for comparison with modern day players like R9 vs CR7, though I dont know how you can argue for the former. Footballing ability aside (and it's still very close in this regard), I think we need to appreciate how high a level you need to be at mentally and physically to single handedly carry the pressures of Madrid for a decade and never drop off, likewise for Messi at Barcelona. No other modern day player comes close to these two.
This is a fair point though. If we look at GOAT across different eras in a comparable way:
50s - Di Stefano (dominate for around 5 years)
60s - Pele (dominate for around 7-8 years)
70s - Cruyff, Beckenbauer (dominate for around 5 years)
80s - Maradona (dominate for around 5-6 years)
90s - L.Ronaldo (dominate for around 2-4 years)
00s-10s - Messi, Ronaldo (dominate for around 12-13 years+)
Least we could do is to compare their length of domination. Its clear only Messi and Ronaldo has managed to dominate for so long, far ahead of other GOAT.
So in terms of domination, the very top tier should be Messi and Ronaldo, follow by Pele, and then the rest etc.
Messi=Ronaldo>Pele>Maradona>Di Stefano=Cruyff=Beckenbauer>L.Ronaldo
Then if we look at their achievements:
50s - Di Stefano (won 27 trophies overall, 5 of them being major*)
60s - Pele (won 30 trophies overall, 3 (or 2.5)# of them being major)
70s - Cruyff (won 23 trophies overall, 3 of them being major)
70s - Beckenbauer (won 20 trophies overall, 5 of them being major)
80s - Maradona (won 11 trophies overall, 1 of them being major)
90s - L.Ronaldo (won 17 trophies overall, 3 of them being major)
00s-10s - Messi (won 33 trophies overall, 4 (or 3.5)# of them being major)
00s-10s - Ronaldo (won 31 trophies overall, 6 of them being major)
footnotes:
*major trophies includes only WC, Euro, Copa, CL
# either injured or out for majority of knockout stages or tournament, and won it playing as bit part role only, could only count as half (0.5) to make it fair
Its clear Ronaldo stands out among all GOAT in terms of achievements, closely followed by Messi, equally match by Di Stefano and Pele.
Ronaldo>Messi=Di Stefano=Pele>Beckenbauer>Cruyff>L.Ronaldo>Maradona
So from the above, here's the GOAT ranking in comparable perspective of individual dominations and overall achievements:
1. Ronaldo
2. Messi
3. Pele
4. Di Stefano
5. Beckenabuer
6. Cruyff
7. Maradona
8. L.Ronaldo
I tried not to compare stats here, as it will always favours forwards. Besides, scoring goals in 50s-60s isn't same as scoring goals in 80s or 2000s. Hard to compare stats across different eras indeed.
In conclusion, no one will take this list seriously though, its just purely for fun in an objective manner. If we go subjective, adding in favour of skills, peak and legacy etc I am sure the list would be totally different.