Still looking...

Not famiar with Eclipse.If you are going by air infiltration #'s the Marvin's would be the worst more than likely. It would depend on what model you chose between the other two brands, but Soft-Lite has a much stronger line up.

The short answer is Soft-lite Imperial LS.

It depends on your criteria. The Infinity has more glass space and a "high-end" look, while the Softlite has better performance ratings across the board, and is typically a better value. They are both high-end choices that are directed at different buyers. The Softlite for ultimate performance and value, the Infinity more for beauty.
I'm not familiar with the Eclipse, and I don't consider Atrium to be on the same level as the other two.

Keep in mind the Marvin's air in filtration #'s are about 14 times more than the LS and are worse than most low end vinyl. Would love to see some thermal shots to compare.

I guess you could say, "It's better at what it does".

If I was considering fiberglass I would want the beauty and performnce both.
If available look at InLine fiberglass to get both.