>>529794872
I would define a good endgame by 3 things
1/ A good incentive
A lot of posters here preach the value of hunting things for huntings sake, but fact is if there is nothing to work towards a lot of them stop playing because despite all their profound cultivation they aren't actually the honing masters they LARP themselves to be.
The reward should be something that inspires new ideas for sets, or encourages you to try out other weapons, this is the primary function of RNG charms but you can clearly take it further with stuff like 4Us, Worlds of Rise's gachas.
I think locking layered armor behind it would also appeal to most people, aesthetics being a reward for achieving whatever the hardest quests of the endgame are.
2/ A good challenge
The endgame has to offer friction, if what it feels like is a treadmill with very little opportunity for failure but a consistent reward then what you've created is not a videogame but a job.
The ceiling for this difficulty should be very high, because you're already catering towards the autismos who stuck around in the first place and are therefore proficient at the game, 4U and Rise both had a scaling endgame but I think 4U is much closer what the final difficulty should be compared to Rise which has a very erratic difficulty curve.
3/ A good variety
Partially defined by the games roster, the endgame should utilize its existing content to its maximum potential to ensure the players don't easily get bored. There were many instances in monster hunter where the "endgame" felt like you just hunting one or two monsters because nothing else was challenging or rewarding enough to be meaningful to hunt. Jobbermons should have upgrades that make them threats, quests should have modifiers that are fun while diversifying the gameplay, maps shouldn't just be one arena, if an endgame isn't allowed to introduce significant new content then it has to use what it already has to full effect.