I think for me personally that the most fun part about destiny is getting to experience something different than before within thr sandbox. The elemental week where subclass trees get reworks and all of that stuff has been the times where this game has been the most exciting to me because it just...gives me something different or similar with a new twist to it. Most notably I'd have to say top tree dawnblade, bottom tree striker and 3 shooter golden gun (I always mix up which tree position its in) are the trees that specifically went from sheer garbage or being bland to some of the most fun and powerful trees in the game. These big changes gave life to some of the most boring or underutilized trees in the game and I have always enjoyed seeing them and experiencing them after reworks and buffs happen. Weapon sandbox updates are exciting too, especially when the weapons I enjoy using go from garbage or meh to good (I always used 600 autos even during year 1, forgive me crucible people). The weapon sandbox improvements add more weapon variety and make gameplay more fresh when done in a good way (5% damage buff to autos back in forsaken was such a joke). But I think the times where the game is absolutely at it's best, is when it introduces new subclasses or skill trees. 9 supers and very diverse skill trees was a highlight of forsaken (even though a good chunk of them were crap due to issues but eventually became good in their own way). And with beyond light coming out, we get a new subclass with a new skill tree (which they said will be more customizable) a new super (or more depending on the variations) and on top of it a new theme. I will always remember taken king for introducing titans to sunbreaker which to this day is still my favorite super by a landslide and even if im bored, it always makes me smile watching everything explode or burn to death in a sea of flaming vortexes. As for weapons, I don't think we got any confirmation of something new but hopefully there is at least new weapon frames of existing types. New content is also important, but sandbox stuff helps me play crap I was previously bored or would be bored of quickly (looking at you reckoning).