Mostly, because it's free (and also because there IS the slight possibility of me needing a flyer or just a body someday, although of course this is an added bonus, I don't take this into consideration at all, but it's nice to have possibilities). I favor the element of surprise better, since when they see it coming, they just play around it. Sure, this also has its advantages, you can either go for tempo or go for the throat. Relic would fit in nicely with gaining tempo. However, most problems I have are with troublesome Kitchen Finks and Reveillark/Puppeteer shenanigans, and either way, I like Macabre better, because it neuters the play they were carefully planning in the latter, and it screws up their combat math in the former. But if graveyard abuse becomes an issue (and I can see it becoming due to the Unearth mechanic), then Relic is definitely better (although I expect artifact hate to become abundant, so you'll just be giving them an extra target, but it's well worth it).