What's the best football team? Who makes the best pizza? What's the best XBox game?
This has been brought up over and over and over again.
There's a FAQ Emporium that lists all the major frontends. Most of them are free (at least for now). You can download them and see which one you like the best for your project, rather than relying on the opinions of others.
You should take into account the specs of your system, the functionality of the software, the look and feel of the software, skins that are available (if applicable), support, speed, etc.
You know your project better than we.