If you're looking for true rounds, I'll have to second the Sunbeams. Between the round core and the precise winding, you'll be hard-pressed to find a smoother and more supple true roundwound.
GHS Pressurewounds ... or any other roller wound string in a lite gauge ...
i have extra lite GHS Pressurewounds on both my 5vers , ... they feel much softer than the DR strings mentioned ( which i have tried ) ... it seems like GHS makes the Smith version also , as the gauges are exactly the same from low B to Hi C ... and YES , they are round wounds ...!!! the outer wrap is wound under more pressure which gives it a slightly oval shape ..! nice feel , reasonable price ...