Suprised nobody has mentioned Black Diamond. They bought out Bibler and make excellent shelters.
The Firstlight and Hilight are 3 season two person freestanding tents that weigh only about 3lbs or less and are very compact. They are small but about the lightest free standing tents around.
I use the Betalight and Megalight. The Mega light sleeps up to four and weighs only 2.5 lbs and pitches with a single carbon fiber pole. If you add the bathtub floor you get a massive shelter with tons of headroom for about 4.5lbs. The Megalight is 1.5 lbs and I made a one pound floor. 2.5 pounds and it will fit two people plus two packs.
Four the four season tents I like the Eldorado or I-Tent. These are standard issue for alpine climbing. The are single wall and BOMBER. They never accumulate condensation on the inside. Best part is they weigh less than 5lbs.
I have no experience with Hilleberg but I know they are highly regarded.
Just my .02