If you are new to flashing ROMs, usually CM 11 is an excellent choice.
However, to me speed, low RAM consumption and good battery life matters, so here are the reasons why I chose that ROM:
1. Linaro toolchain - Here is a link to explain why it is faster than standard CM:
2. Dirty_V kernel - For speed, most of us Nexus users feel it is the best. It is an improvement over Franco's kernel
So, I usually choose a ROM which uses the linaro toolchain. I also got a ton of cool features like notifications, omniswitch, etc. which you can read about in the ROM link from my previous post.
In the end, I am just giving you suggestions. Why don't you try creating a nandroid backup and then flashing many ROMs to see which one you like? Using the nandroid backup, you could always come back to the tried and trusted CM 11 !
Here is a small intro to nandroid backups which may be useful even in the future in case you mess up your phone with a bad update:
Hope this helps!