Mobil One 10W-30. $$$ Millions of research dollars have been spend on automotive oils and as a class they are outstanding lubricants. Diesel lubricants even have more additives and I am going to try a bottle eventually. I am of the opinion that gun oils are repackaged industrial oils or plain mineral oil without additives. Not worth spending a premium for.
I also like LSA but after lubing with LSA and leaving a rifle in long term storage, the stuff migrated into the buffer tube and it was a mess to clean out. Proves the stuff lubricates.
The real bottom line is that rifles are not that severe of a lubrication envirnoment so anything that is light and works in a more severe application, like cars!, will provide all the lubrication an AR needs.
Just keep it wet.
If I'm not shooting, I'm reloading.