For me, it's seeing the very last few poke up---so I know everything survived the winter. I usually leave the mulch on until the very last possible minute to hold stuff back as long as possible to avoid late frosts. Except for a few bulbs the voles got, everything else is up including the Spring planted bulbs. This year, stuff underground fared better than stuff above ground. My peach trees and flowering shrubs took a hit from the extreme winter cold. Everybody's evergreens look tough; even large white pine trees suffered.
The only problem I have now is that I moved one of my best lilies last Fall and now I can't find it!
It's here--somewhere. I guess it will remain a mystery until it blooms.