In the near future, I have to update a bigger XPage application (development time more than three years) now running on a Domino Server 8.5.3 FP6
to Domin
I use oneUI at the day job. There are some very good things about it. However, I'm trying to get my company and all my personal work migrated to Bootstrap. OneUI is not really responsive. Even if that's not a big issue for you the biggest reason to avoid oneUI is the lack of documentation and materials for it. There actually is documentation for oneUI But nothing like Bootstrap - the most popular framework going as far as I know. Heck right here on StackOverFlow over 59,000 questions have been asked on Bootstrap. There's tons of resources like bootsnipp.com. In my opinion it's almost a no brainer that Bootstrap should be used over oneUI if at all possible.