If you asked Lady Sylvanas Windrunner what meant most to her when interacting with her people, her answer would be respect. She refused to be disrespectful to her Forsaken, knowing that it was a two way street. She had once thought of them as arrows in a quiver, meant to be expended when she needed, she thought that way no longer. Respect must be earned.
If you asked Lady Sylvanas Windrunner what meant most to her when interacting with her enemies, her answer would be vigilance. One never knew when an enemy would pull a dirty tactic, and though Undead, she wasn't immortal. Vigilance was survival.
If you asked Lady Sylvanas Windrunner what meant most to her when interacting with her loved ones, she would scoff. The Banshee Queen had no loved ones. Her sister Alleria was long gone, Vereesa was allied with the Alliance, her parents and younger brother were dead, there was no need to dwell on the past. She had attempted to regain Vereesa's love and trust, and that only ended in pain. The past was an amalgamation of pain, fury, sadness and negativity.
If you asked Lady Sylvanas Windrunner what meant most to her when interacting with Aelwynn, her voice would turn contemplative, as if the notion of the irreverent Blood Elf hunter being in Sylvanas' presence was something to look forward to. Contemplation of the future, that was where her mind went when Aelwynn was around.