I really liked Kes, I rank her as my second favourite character on VOY (after Torres and before Tuvok). Her relationship with Neelix was always cringeworthy, so I was happy when they split them up as she was no longer Neelix's girlfriend and could start to be a character in her own right.
She was a sweet, warm, 'innocent' character, who deserved to stay. But there is a real passion and awe to her as well, her line in Caretaker ("I saw the sunlight") was excellently delivered, that you just felt her joy and wonder at something so simple that we take for granted.
She was a far more interesting character than Seven. I sometimes wonder what would happen when she entered the Elogium, who (if anyone) she would choose as a mate.