On iPhone, so far "Go Map!!" works well for my simple edits, which are things I notice while walking on the sidewalk.

https://wiki.openstreetmap.org/wiki/Go_Map!!

(The double exclamation marks in the name drove me away initially, so I tried 3 others first, none of which worked well on the iPhone for my edits, but then "Go Map!!" seemed to just work.)

For edits that can be done from desktop, the OSM official Web site's editor was pretty good -- complicated, but seems to work, and has a nice interactive tutorial mode.