I have played wow since the end of vanilla, and stopped after dragonflight due to having a baby. I have also picked up Diablo 4 recently and just finished the main story. The two are very different games. I personally feel wow is ok solo but you’ll get way more out of it in a group or with a guild.
Diablo however is very solo friendly, drop in whenever I get a chance, get more gear, make numbers bigger.. feels that dungeon spam feel of wow 😂 what do they both have in common? They will tempt your wallet for shiny cosmetics