That one moment you installed that QoL mod and you could never live without it ever since you tried it. How about that one combat mod that you had fun with, what about the Structure gen mods filling up your adventures. Lastly the decorative mods like furniture and stairs and slabs. I almost forgot "Voxy" giving you that sexy render distance of 64+ blocks enhancing your Large Biomes world. List goes on and on.
I just can't decide whether to stick with Vanilla or keep on Modding to the fullest extent. Woosh, how overwhelming my experience was at the same time very fun.