I feel like out of the three brothers, Renly is the happiest because he was with the love of his life. And while he died he managed to die with something precious, while Robert died with regrets with how he treated Cersei and felt like it was his fault Joffery became a monster and that the love of his life Lyanna passed away and probably didn't want to believe she was in love with Rhaegar and left with him willingly.



And Stannis may not be dead yet but he has a miserable life at this point, he burnt his daughter at the stake, his wife killed herself and is losing a battle.