I don't know how you know I play Destiny 2 but....
Destiny 1:
Literally non-existent story within the game. You had to go online to learn anything of lore.
The most toxic and infuriating PvP system of it's time (this coming from me who went 9-0 in trials over 15 times)
Unnecessary and sometimes even infuriating amounts of grinding due to horrible RNG (played since week one and never reached max light, hard/challenge mode completion of last raids, or completed a shader, emblem, armor, or exotic collection.)
Destiny 2:
Half-Decent story, if you didn't research the lore in 1, you won't hear it in Destiny 2.
An evolution upon the most toxic and infuriating PvP system I'd ever seen... I think it now may be worse. If you don't own "The best weapons in the game" You can't compete... even with shotguns and snipers now moved to power items (which I don't agree with snipers being moved) its simply made the game even harder you almost need impeccable aim and either a fast accurate auto or a mida multi-tool to succeed in the game with its current state.
Grind to actually hit level 20 for me was the worst part... did not enjoy the story as it felt grindy and repetitive on every planet... only two really good missions in the story. After hitting 20 raising your power level is not hard in the slightest... until you hit 265... then the grind is pretty insane so at that point I just kinda step back and start other characters.
Changes to the shader system angered me so much I'm actually refusing to put any money into Destiny beyond the base game.. No DLC, no micro transactions. Activision basically screwed us as day one consumers at the end of the game taking over $150 from us minimum if we played all the way through while new players could get the whole thing for $60.... THAT LARGELY DISTURBED ME. Worst part is they will do it again with Destiny 2 and I'm not playing along this time. I'll wait till its dirt cheap at the end and then enjoy DLCs if I decide to.
Overall if things like the above trigger you, avoid the game. Warframe is a far better multiplayer experience, and Overwatch is a far better shooter.