I am searching for a lightweight backpacking tent. under 6 lbs
1 or 2 person is fine and some 3 person if it light enough.

The list of good 2-man backpacking tents is long. There are several that IMO rise to the top of the list. Two doors and two vestibules are important because that allows a pretty small (and therefore lightweight) tent to be used comfortably by two adults.

The REI Quarter Dome T-2 is a 3-season dome tent that has been around for over a decade and it remains a favorite of many backpackers. It weighs 4#.
https://www.rei.com/product/110819/rei-co-op-quarter-dome-2-tent

The MSR Hubba Hubba NX-2 is the newest iteration of the Hubba Hubba tent. It weighs a little lass than 4#.
https://www.rei.com/product/863076/msr-hubba-hubba-nx-tent

The MSR Dragontail 2-man tent is on sale at REI. It is a 4-season tent and weighs about 5# and that's extremely light weight for a 4-season tent. It's not a free-standing tent but that's a deal will be hard to beat.
https://www.rei.com/rei-garage/product/115998/msr-dragontail-2016-closeout

Almost certainly there will be some proponents of tipi style tents that will chime in. I'm not a fan of tipi tents. I prefer dome tents. But I'm not going to get into why, because I don't want to reopen old wounds.

KC

I hate mesh. If I was hiking the Appalachian trail in mid July maybe I'd use a mesh tent. But in the Rockies I prefer to hold the heat in--mesh doesn't do that.

Companies today are infatuated with telling us we need bodacious ventilation or we're all gonna drown in the condensation in our tents. Not in the mountains where I hunt nor the time I spent hunting in Alaska during September where it rained 15 out of 17 days have I had much of a problem controlling condensation with tents where the mesh can be covered.

Plus, I've been in well regarded mesh tents when we get those afternoon monsoons during archery season at 10k+ ft and it rains so hard the runoff from the fly pools up, and the raindrops hitting that pool of water splash up between fly and tent, and before long water is dripping through the mesh INTO the tent. I've also had the wind blow water between the fly and tent with the same effect.

AND, when it snows I've experienced spindrift filter through the mesh, or collect on the mesh and melt......again with the same drip, drip, drip.

AND, when backpacking in Utah with a group of people with those well ventilated mesh tents, they discovered mesh does a GREAT job of filtering out the larger grains of sand blowing around and only allow the very finest (sic) of sand to coat everything inside.......

I'm in the market for a new lightweight backpacking tent too, and I have pretty much narrowed my choice(s) to the Big Agnes Slater SL, or the Foidel Canyon. I have not used these tents. But last year we backcountry skied and the other pair of guys had the Foidel Canyon which I liked a lot. I've also had the opportunity to compare the Foidel Canyon and Slater SL at Big Agnes in Steamboat when they had them set up side by side. They also have a Slater UL which is lighter than the SL, but I don't know what the differences between the SL vs UL are.

All three have the ability to zip nylon covers over the mesh.

Casey

Look at TarpTent. 6 lbs is on the heavy side for a two man tent. You can get a 3 man TarpTent that weights about 3 lbs. I've got two TarpTents including a 1 man ProTrail for bivy hunting and a 4 man model that my kids abuse. They perform quite well here in western Colorado.

Wife and I have used floorless off and on for years.

When you carry it all, the weight savings just makes sense to us.

AND you can get a much larger footprint for the same weight.

Just our part of the opinion.

Here you go:

3.5 Lbs and you can run just the fly/footprint if' you want.

Big Agnes Copper Spur UL1

Here's a floorless option at 5.8 lbs all in (canopy, CF pole, stakes). Seek Outside 6-person tipi. 7'10" peak, 14' diameter.









https://seekoutside.com/6-person-tipi-pre

Where are you using it?

Out east, I'd want a floor and sealed up from the critters along with good ventilation for the potentially warmer temps and higher humidity.

Out west, the tipi is the bomb. My Seek Outside BCS with a Ti stove is truly the greatest thing since sliced bread! Light, comfortable, and a stove to stay toasty or dry stuff.

Fwiw- my vote is for big Agnes flycreek ul2.. I'm am a big fan of ULTRALIGHT.. but I'm usually alone.. bit small for two unless the weather is good.. if it's bad my gear can go inside with me easy.. it has a vestibule for boots and my KUIU ultralight pack but very tight for 2 WITH gearinside.. CRAZY lightweight .. and strong .. picked up 1 here on the fire almost new for almost half price.. I think it was 150 or 175 and the guy threw in the footprint too.. check craigslist also..
BEST TENT EVER!! crazy lightweight and Very well built.. that being said this is more of a 3 season deal not deep snow or hurricane winds..

Sixmoon Designs Lunar Duo

https://www.sixmoondesigns.com/collections/tents/products/lunar-duo-explorer

This

Not enough information for any recommendation... you may want to give more specifics about its purpose.

Where will it be used?

What seasons will it be used in?

How many people do you actually want to fit in it? A 1P tent is quite different from a 3P tent.

Out west elk hunting in SAN Juans around Durango October. I need 2 man backpacking tent.

Google Hilleberg Nallo 3gt.