If you find an ENB with a colour pallet that you like but are not happy with the performance loss, it is very easy to tweak as well.
You can adjust the quality of specific features in-game by presssing shift+enter or by editing the enbseries.ini file.
The values are as follows:
-1: Extreme
0: High
1: Medium
2: Low
ex.
[SHADOW]
DetailedShadowQuality=-1 (you can change these numbers to get better performance if needed)
ShadowDesaturation=0.5
I only share this info because many ENB presets are borderline unplayable on good systems as they rarely playtest the entire game in them.
For presets, some people like Dynamo but turn off his FPS limiter (enb fps limiter is shit) and select a lighter DOF. This one looks nice in the base game but tanks hard in Dead Money and the Underwater Hideout if you use that mod.
Another one is Rudy ENB; I am personally not a huge fan but many people enjoy it. He also tries to keep his work in line with the newer binaries.
At the end of the day though, there is no "best" enb. They are subject to personal preferences and you should pick what looks good to you.