Khorne: Nurgle is too slow , lazy and indirect, but he is resilient. Tzeentch is a coward, using trickery and magic to fight his battles, but he is a good strategist. Slaanesh is an insult to the word “deity”, a fop who spends all it’s time on pointless self-indulgence and meaningless “games” that do nothing but waste time.
Tzeentch: Khorne is a brute, a blunt instrument, if an effective one. Slaanesh seeks new thrills and horizons, but cannot reach for anything more meaningful than self-satisfaction. Nurgle is an abomination, a rotting heap of flesh who exists only to tear down great things, stagnate potential, and bring low all that is or could be.
Slaanesh: Nurgle causes pain aplenty, but he numbs it far too often, and has no sense of art or aesthetics. Tzeentch is wild and unpredictable, always something new, but is stuffy and boring, never enjoying what he has or will have, bogged down in minutia. Khorne is a knuckle-dragging ape, a blood-thirsty buffoon who always wants the same old thing over and over and over. No sense of thril or enjoyment, just dull bloody business. Literally.
Nurgle. Khorne is an angry chap, but strong and his battles leave behind wondrous masses of flesh and blood to rot and nourish the soil. Slaanesh is a bit too focused on play rather than work, but is like me loves it’s work and appreciates the cry’s of gratitude* from its lovely subjects. Tzeentch is a busybody, always sticking his beak into other peoples business. He has no care for anyone but himself and keeps interfering with everything, always trying to shift things to his way, always making things convoluted and piling more onto something to “fix” it, rather than letting nature take it’s course and let things break down to be made anew
*AKA Cries of pain and despair