I believe Rick Steves are the lightest and also the cheapest. Both important arguments.

When choosing packing cubes it is important to look for two things. The right dimensions so they fit your bag and the fact that packing cube is most useful if it compresses the contents inside. Only if it compresses the contents will it save space. Thus it is best to pack sweaters, underwear and knits in the cubes. These items can be rolled and compressed very nicely. If you follow that principle, it will be easier to get compression from a FLAT packing cube rather than a high one. That, unfortunately, kills the RS because they are the highest. Of course, it depends how you pack and what you pack but in general the rule is true. Also if you are traveling with a bag like the BR 235x or the Airboss, the compartments are rather flat. It thus makes sense to use flatter packing cubes. Naturally, you could just use a fatter cube and let the bag compress it but that will lead to bulging negating the "neat" effect packing cubes should have.

So look at the ebags and the EC and then choose the one that best fits your size needs and decide how important the weight difference is. I think ebags is heavier but I am not sure.

Till