If there is any sort of a need of friction with the personal term, then I'd oblige and give a more concrete answer.
The most meaningful part would be both the small and short times where I am left to myself and my mind--some thoughts and remembrances, and my days with a few other, friends and family. Some of them are powerful enough to shape my future enterprises (academic that is), others enough to make good times...memorable.
Though in a less constricted manner, without the presumption of some sort of temporal basis, or perhaps even a personal standard, I would agree that art is very meaningful but human achievement and humanity more important. I would value the human spirit, especially in the very act of creating and making something fruitful, the most, even if I can only describe it in general terms that cater to my perception.
Ignorance more often begets confidence than does knowledge."--Charles Darwin
"I believe that the mind can be permanently profaned by the habit of attending to trivial things, so that all our thoughts shall be tinged with triviality."--Thoreau