Hard to recommend themes. Most common popular apps are springtomize 3, winterboard, bitesms, zephyr, activator, and many others.
I found the best way to start was to keep up on the forums and follow the "Post your homescreen" threads as they are full of great examples of what can be done
The best part about jailbreaking is looking for tweaks and themes that you like. Like Tmlfan3 said, look through the threads here and see what other users are using and go from there.
Google things like "Best iOS 7 Cydia Tweaks" and you will find plenty of bloggers who have shared lists of their favorites. It's a good way to see what's out there.