Not saying that Doc is, or should be the bar for the Hall, but his career was definitely more dominant.
Just using fWAR
Seasons at or above 5 FWAR: Greinke 3, Doc 8
Seasons at or above 6 fWAR: Greinke 1, Doc 6
Seasons at or above 7: Greinke 1, Doc 2
Seasons at or above 8: Greinke 1, Doc 1
Basically Greinke had 1 elite season and 2 great ones, Doc had 3 elite seasons and 5 great ones.
Greinke also had 3 seasons at 4.8 or 4.9, so one could probably give him some extra credit there.
Docs peak was basically 2001-2011, 62.9 fWAR over 11 seasons. Exactly 2300 IP, 319 starts and put up a 2.98 era, 3.08 fip, 3.16 xfip
Greinkes peak was 2008-2019, 54.2 fWAR over 12 seasons, 2416 IP, 376 starts 3.11 era, 3.19 fip, 3.34 xfip.
Greinke was pretty solid, #’s are pretty close. Halladay definitely better but not by a large margin.
Greinke easily has the longevity factor, he will have 7 seasons outside his peak, though none of them have been anything other than 2 fWAR or lower.
The way I see it, both have identical fWAR over their career as it stands right now Greinke 65.5 vs Doc 65.4. Doc did that in 15 seasons with the vast majority of it in that 11 year peak, it’s taken Greinke 19 seasons.
Halladay better, Greinke a tier below.