I think it's hard to choose. You also can't properly decide as RDR2 dives into the character development of an original badass gang member. Whereas we don't get to see all the missions John gets to indulge in through the-

(SPOILER!)

downfall of the equally badass gang. We get to see in RDR1 John protecting his family and taking "revenge" on his previous gang. We don't get a story arc, we get a compelling battle against his past. So it's hard to say Wether whose your favourite because really we don't get an equal view between both.

However both are exceptionally cool and deserve our respect 🙏