If you are serious about developing easy to maintain websites, and create beautiful , intuitive user interfaces for WordPress, then Advanced Custom Fields will not disappoint.
I use all the premium add-ons (repeater, options, gallery and flexible layouts). It's just unbelievable what you can achieve with this package.
Imagine being able to insert any type of content anywhere on your site, sliders, testimonials, FAQs, you name it.
Support is also excellent. Bug fixes are released quickly when reported.
I can't recommend it enough.