Marmit (left)........... SS (middle).......... Medicom(rt)
Marmit is still a great figure. SS is very close. I think the pose you have the Marmit in (belly out, shoulders back) is just a little better than the SS, so it helps make the Marmit look better.
Pretty much a toss up for me. I have a Marmit myself so I'll have to get it out and compare as well. I like the subtle variations between the two so I'll enjoy having both on the shelf.