The reman one could be okay if it comes from someone reputable. But a reman could just as easily be a crack repaired head. A warrantee is great if it includes labor, which it likely wont. Generally their warrantee only extends to replacement.

A new head from MB would be fully warranted, labor included, "if" the dealer installed it. Anyone else and its a maybe. But that would likely be very $$$$$

Me, I would go for a good used one. A good used head thats never had any work can be a very good choice and is the least expensive route.