I'd go with Lost Hours because anything from Time Spiral block is automatically cool to me. However it's a bit weird in not fully getting rid of the card, so it doesn't fit as well in grindy midrange or control decks that care about CA over tempo. Also, it's the kind of card that some players might look at and think, "that's so bad, they're still going to draw into it eventually!" Learning to think like your least experienced player has been really helpful to me.
So if you decide Lost Hours is too wacky, I'd choose Lay Bare the Heart over Addle because it's going to miss way less (which feels pretty terrible), and you already have Transgress the Mind to snag big legendary creatures.