I'll start this contribution thing off with one of my own...
I knew Eileen. I didn't know her "the most", but I knew her very differently than anyone else could have possibly known her. Our relationship was unique.
Eileen was my mom and while I was only one of three children she had, things worked out so that it ended up being just the two of us... I mean, mom's first born, Warren, died at 4, then my sister Kathy at 18, then mom and dad separated and.. Well, the year was 1985 and I was 13 and it seemed as though overnight we went from being a normal every day family to just mom and me, bound by and caked in layers of grief.
Everyone loses someone, eventually anyway, so in a sense grief is a universal experience. I've lost track of how many times a friend or colleague has lost a family member and I've heard people say to them "I know just how you feel..." But my own take is that every loss is different and everyone's grief is unique, intimately unique.
Me, I've lost my sister, my dad and my mom. Each relationship was unique, each death hit differently, each loss was a separate and distinct and fundamentally singular experience. You don't get better at dealing with death each time you lose someone. It's all different, every loss is the first loss and no one else truly knows how you feel.
Another thing about grief - it's not a competition.
When Kath died I used to think "I lost my sister but mom and dad lost their child and that's worse". Well it's 30+ years later now and somewhere along the way I came to realize that there is nothing worse than losing someone we love.
When Eileen died, I lost my mom. My son lost his grandmother. My uncle and aunts lost their sibling. And many others lost a cherished friend and colleague. No one's loss was any greater or any lesser than another's loss. Grief isn't a competition - it's a loss unique to the relationship, shared experiences and memories. 
