If you're looking for an affordable fully-opening quilt for summertime use, the Hammock Gear Burrow 40 is a great choice. Hammock Gear produces a full line of top and bottom quilts for hammock hangers, and the Burrow 40 top quilt is a great ultralight sleeping bag for ground dwellers too. For use on the ground, snap the footbox closed and purchase the pad attachment kit to mate it up with your sleeping pad. This summer weight quilt is the second lightest product we tested in this year's ultralight sleeping bag review.
If a fully opening quilt is what you seek, we prefer the Enlightened Equipment Revelation 20, which won our Best Buy Award. We tested the 20 degree model of the Revelation, which is more appropriate for three-season use in part because it has a zipper to close the footbox rather than snaps (like the burrow). The other fully opening quilt we tested, the Feathered Friends Flicker 40 UL, zips completely closed to function as a mummy bag.