I have hypothesized that the Maltron feels spacier than the Kinesis Advantage because the Maltron has spherical keycaps compared to the Advantage's DCS family keycaps. I did some rough measurements, and the spherical keycaps have less surface area on top of the keycap, so it does increase the space between each keycap. I also enjoy the uniform feel because all the keycaps are the exact same shape. On the Kinesis Advantage, I didn't like how the rows were all different heights, and with the spherical keycaps, the rows are almost flush.
Without further ado, here are some pictures. I couldn't resist a ridiculous American flag design theme to the keycaps:



