I use the tercarta bible app.
I have it on both my iPad and phone, you can add different coloured
highlights, copy and paste from it (I use that when referring to verses
on here), add book marks, make margin notes, email and print it out etc.
You can look up cross references and foot notes. Also you can copy
chunks across to other apps like one note, notes, word etc. So it's
good for using in research or serious study.
You can also sync across devices so all your notes and highlights appear
on all devices.
There are loads of versions of the bible to download (most are chargeable)
and you can view two parallel versions side by side to compare them.
Once you have downloaded what you want there is no need to go on line to
use the app, you only need to go on line if you want to sync across your devices.
It also has a text speech facility so the text is read out, although this
sounds a bit robotic. Hopefully they will change that at some point.
Ive used it for a couple of years without any problems and find it
very good.