When I had the GNex I used Lean.Kernel. When I had the HTC Droid Incredible I used both Franco.kernel and incredikernel. With my Nexus 4, I use Franco.kernel. If Lean was available for the Nexus 4, I'd probably be using it. However, I must admit, Franco.kernel is pretty amazing on my Nexus 4. I just flash and go. With his kernel, I get hardly any lag on poorly coded apps, such as Tapatalk 4, which, in all fairness, must support legacy Android devices which is probably the culprit of said lag.
As has been stated, flash a kernel and test it out for a bit. See how you like it. Then try something else. Your mileage may vary.
jmar