Online ads, they were so annoying to deal with, I tried Adblock (don't use it) then ABP (don't use it) then finally I found UBlock Origin (absolutely use this) and just seeing the amount of unnecessary connections on every single website annoyed me even more. On mobile I used Adaway and looking at the logs for that annoyed me so much I switched to LineageOS.
I "upgraded" to windows 10 and I couldn't deal with how annoying it was with all the bloatware and random notifications so I switched to linux