LinkeSoft SongBook

The most compatible music reader app - as long as you only need ChordPro.

unrealBook

You just gotta love an application with a transmogrify button.

MobileSheets (Pro)

Odd user interface and odd update policy -- too bad for an otherwise good app.

Fakebook Pro

The Fakebook Pro is my app. Featuring the functions I need. Working in the way I want. Perfect for my gigs. That's it! But judging from the popularity of the app, the Fakebook Pro might be right for you as well.

GigBook

A good PDF reader app with some really nice extras for musicians. Unfortunately the latest versions seems to have stability issues.

forScore

On iOS the forScore app is the score app, by many considered the golden standard. And for good reason.

Musicnotes

The free Musicnotes app is first and foremost a frontend and viewer for the Musicnotes.com sheet music store.

piaScore

Perfect for getting started with PDF sheet music. Avoid if you need flexibility.

Woodshedr

Woodshedr is an iOS app with great potential. It shows music, chords and rhythm in a familiar staff format, crisp and clear.

iReal Pro

Excellent for private practice, but depending on your needs it might not be the right choice for your gigs.