How do I choose between raid, Mythic Plus, PvP, and delves?

Site-seeded discussion prompt: new and returning players often ask which endgame mode is best. What should someone pick if they have limited time, no guild, anxiety about groups, or a competitive streak?

The right answer depends on schedule and tolerance for social friction. Delves and casual PvP are easy to sample; raiding and high keys benefit most from a stable group.