Of the two, I'd prefer Claws, because it lets me get the card
while I'm hating on the graveyard... but, for the same reason, my actual selection might end up being
Relic of Progenitus? Depending on how many cares-about-bauble-and-graveyard things you have.
There's a surprisingly large number of things to consider:
-how much does the card do the instant it arrives (Lantern > Claws = Relic, because it hits a single target card rather than a single card of your opponent's choice)
-how much do you get for zero additional investment in mana (Lantern > Claws = Relic, because you get an entire graveyard versus one card per turn of opponent's choice)
-the exact opposite of the above line, something like "can grind your opponent's graveyard slowly but repeatedly" (Claws = Relic > Lantern)
-how quick is it to hit an entire entire graveyard (Lantern > Relic > Claws, because it's 0 mana, 1 mana, impossible)
-whether or not it hits your own graveyard (Lantern = Claws > Relic, obviously)
-can you get the card while still graveyard hating (Relic = Claws > Lantern, 1 mana investment vs not possible)
-can you get the card while NOT graveyard hating yourself (Claws = Lantern > Relic, 1 mana investment vs not possible)
-ease of recursion (Lantern > Claws > Relic, because Lantern can put itself in the graveyard for free if you don't need to cycle it, Claws takes 1 mana, Relic always exiles itself)
I think I'd pick Claws if you expect anyone wants to keep their own graveyard intact, because when Relic wrecks your own fun plan it's such a feel-bad even if it's right. When it comes down to Claws vs. Lantern, I think of them - totally unfairly - as
Scavenging Ooze vs.
Tormod's Crypt. If that incredibly insane comparison helps any, uh, I'm glad!