Crossover - Make your bets, people... But whoever wins, we lose.

I guess this depends on what you consider a win/victory for each creature.

For the Blob there's no real motive to its existence it just does: It's like an amoeba, it has some self-preservation to stay alive, but it really doesn't give a shit. Just keep growing and growing.

For the "Thing" it's a different story, from the John Carpenter's movie we get a sense that the "Thing" has some sort of basic plan to replace everything. It's clearly mechanically advanced seeing how it disabled vehicles, and designed a rudimentary hover vehicle to escape the Antarctica. It also gains the intelligence and knowledge of whatever it absorbs/copies or assimilates. It might be possible for the "The Thing" to discover the cold weakness of the Blob, but trying to copy and assimilate the Blob could fail since the Blob is just a living mass of eat.

The only reason I care who wins is so that I know whether to invest in flamethrowers or liquid nitrogen.