Modoohut's exDialer application, an extremely light-weight, easy-to-use, theme-able dialer app, brings a lot to the table as yet another alternative to Android's stock dialer, especially considering that it is totally free.
At A Glance
Though exDialer's theming options are impressive, the default theme itself (inspired by the famous MiUI ROM) is gorgeous, and I haven't exchanged it for another skin since first downloading the app weeks ago.
The app itself is exceedingly easy to use, and has a footprint of a mere 1.35MB, making it lightweight. The only drawback in this respect is that exDialer automatically installs exContacts, an app that basically serves as a shortcut to exDialer's built in contacts system.