CarbonRom is an AOSP based rom, which is always compiled with the latest linaro toolchain. The kernel also is compiled with -O3 optimizations for better performance. It also gives you a great option of customization.
Reasons to go for CarbonRom are:
- Compiled with Linaro, this will make your phone ultrafast and ultrasmooth
- AOSP based, s no bloatware or other stuff
- Great Customization options
- Nice look
- TWRP Recovery
Although its in alpha stage but you can give it a try and enjoy its awesome features, and encourage the developer, krabappel2548 to do more work on it to make it stable..