If you want a pure, debloated Nexus/Google TV experience with no custom UI lag.
For 90% of users, the latest official update from the vendor is the best option. These builds are specifically tuned for the thermal limits and driver requirements of the 825x Pro chipset. 825x pro firmware best
The engineering team has moved away from incremental patches. Version 4.2.1 is a of the core scheduler and network stack. Here are the headline features: If you want a pure, debloated Nexus/Google TV