Good Paid Apps for iPhone 4?

I just got my $100 itunes card with my macbook air 2013, and I've only bought 2 apps i've really wanted, the entire top payed apps have terrible reviews or just don't appeal to me. If anyone ever payed for an app and use it all the time, and it works well with the iphone 4, please tell me I really need some apps. Also I don't play games because they kill my battery just passive games like tiny tower, or flow.