Art exists to evoke a response in the consumer of it. An explosion will create any number of emotions in the people it affects, as would an ageless puppet. Even if those feelings are fear, revulsion, anger, sorrow, etc., the point was to bring those emotions to being. In a way, Deidara and Sasori are both master artists, especially given how they react to each other's art. They squabble over execution like Picasso and Matisse, and fail to realize the power they truly hold. Their fight holds roots in their own personal insecurities regarding their style, and the saddest thing is that they never really resolve it between them.

On the one hand, Sasori hits his peak, and by his definition he can do no more, so he is content to return to the Pure World. But Deidara's style means he can't peak; there's no pinnacle or monument that will ever stand as tribute to his artistry, so once he is revived he has no choice but to continue constantly creating. But, in a way, he likes that this is the case - he isn't compelled out of fear of being forgotten, but out of need to create.

So, in a way, they both achieve the lives they wanted. I can't say that I think one has a better definition than the other, considering they lived truly to their own credos.

Indeed, Living up to your own standards is the first rule of finding true inner happiness and peace,
Sasori and Deidara both work hard at seeking their own pathways and answers to life's greater meanings.

Idk if they found them before or after their deaths, but they both certainly lived and pushed their selves to their upper limits