When flying other than business, I usually look at the number of lavatories for each cabin. If the united flight provides access to one or both of the lavs right in front, then I would go for united. (4 Lavs seems like a lot for 1 business section). Otherwise, if flying ANA, it depends whether you fly the newer or older cabin. The older cabin has 5 lavs shared with both PE and E, while the new one just has 4 for more seats! (Source aerolopa). Personally I would pick ANA for the food and service, plus I dislike the 787 dimming windows which some airlines block into dark mode.