As long as the Ending is not like Oshi No Ko, I can accept any kind of ending. A completed novel is better than an incomplete, no matter what. At least there's a closure.
I do like the occasional bittersweet ending. One that stood out to me was a manga called xxxHolic. The protagonist barely escaped a birth prevention paradox by sacrificing his ability to be remembered. To all of his friends he would never be more than a stranger, and his parents straight up never existed. Still, he was alive, and he even managed to protect his friends.