I like later more.

The second one with the golden border is more appealling for me

I prefer the former, based on the group shot in your library, squads will stand out on the tabletop. 

Depending on whether they are codex compliant, you could reserve the black pad for Sergeants or other ranks - it does look good with the gold border.

Just my tuppence - both look good!

Rusted Boltgun covered all the thoughts I had. I do feel using one scheme for regular marines and the other for characters or elites would work well and enhance the distinction between the two on the tabletop.