I chose the sacrifice. It wasn't really a tough choice, I knew I'd be really unsatisfied if Grima was left alive. The really hard choice for me was in the chapter before, when Chrom wants you to promise you won't do it. What I really wanted to say was "I won't plan on doing it, but if there's no better choice, then I can't make any promises." MU didn't really say that though, it was more of a "I'm really sorry, but it's my choice." So I felt pretty bad about that.
And I was pretty depressed during the credits and all, I was hoping you'd survive it on the spot, and it was pretty heart-wrenching seeing everyone look off into the distance and hope you're still out there. I was nearly crying at the End screen. I knew I made the right choice and all, but later on I started feeling really sad about the choice again and tried the other ending. Sacrifice is definitely the preferred choice for me. Chrom sedating is definitely the more superficially happy ending, but yeah, I was too uncomfortable with leaving Grima alive. What really sets the sacrifice as the better ending is the stinger. I'd really resigned myself to the game just saying "Maybe they meet again who knows," but the cutscene was just so incredibly heartwarming and comforting. It was the perfect way to end the game for me.