Ignoring the lack of updates if the game is buggy, games back then were also more focused on quality and make gamers replay the game with unlockable features based on skills, not money. I can't count the number of times I played Metal Gear Solid games over and over to unlock new features playing the hardest difficulty and with handicap features, and also to find Easter eggs. Speaking of Easter eggs, you'd lose a number of hours exploring every nook and cranny finding them!
I think it’s really hard to quantify. They are both masterpieces even if you just consider the state they are today and not just the era they are made in.
Sure Red Dead Redemption 2 has “better graphics” but Link to the Past looks great in its 16 bit art style. I wouldn’t want to change the graphics. I don’t think A Link Between Worlds or the switch remake of Link’s Awakening improved the graphics for instance.
Red Dead Redemption 2 might have “deeper” gameplay mechanics but I don’t actually care for them very much. The cores system I think distract from the game, and Arthur is honestly a bit slow and clunky to control during fights; unlike A Link to the Past where fighting with the sword is smooth, blocking with the shield is easy to understand and the items add a element of strategy to the combat.
Ultimately I think that red dead redemption 2 is the better game and part of it is because the modern era it is in allowed the developers to tell an story and create a character that I was invested in more than any other in gaming. But ultimately I think it comes down to personal taste. Earthbound is another game that made me feel similar to RDR2 as far as story beats go. And if I had to pick one game to play for the rest of eternity, I’d be fine with either choice.
Nice thoughtful reply where I think you mostly catch my feelings as well.