A few caveats apply. First, this is just a sampling of the gear that I've used. There are many other options out there, and some I'm sure are equivalent, lighter or better.
Second, my gear is slightly biased towards North American suppliers. In part, this is because I'm from the States (though I've resided in Scotland for awhile now), and travel there regularly.
Third, tent preference is personal. Like many choices in backpacking, there are trade-offs. I'm happy to sacrifice some internal space in exchange for a lighter tent. Others might be happy to pay a slight weight penalty to have more room. It's all good. The goal is to have fun.
Eureka Solitaire (Gossamer)
Eureka Gossamer on the Appalachian Trail
This tent served me well for many years. It's a single person tent, and requires pegging out to stay upright. It features a mesh interior, and over this an attached fly. Inside, I've found, there's plenty of room for my sleeping bag and pad, and I fit my pack either in the front of the tent or inside the front fly.
There are three big advantages to this tent. First, it's light: 1200g or 2 lbs 11 ounces. Second, it's relatively inexpensive (< £100/$100). Third, I found it to be excellent at withstanding the rain, at least for the first several years.
It is small. You can't stand up in it, and there isn't a lot of head room. My sister had this tent and didn't like it because she felt it was slightly claustrophobic. So it could be best thought of as a spacious, breathable bivy.
On a section hike on the Appalachian Trail, the trail held up wonderfully in a heavy rainstorm. After several years' use, it was slightly less waterproof on a rainy section hike of the West Highland Way. However, I've found generally that tents tend to lose a bit of their water resistance after several years.
In short, this tent or its equivalent is lightweight, good value and functional.
Sierra Designs Lightning X2
In the Rothiemurchus Forest
I love this tent. It's a small two-person tent, with a mesh inner and a separate fly. It has this slightly odd pole system where there three main poles are all attached to one another, so it's essentially one pole. It has a front and back door, which is great when there are two of you. I've used this on the T.G.O. challenge (see the top photo on this post), and still use it when camping with my son, who is not quite a teen yet.
Advantages: The tent is bullet proof. If I know there will be heavy rain, this is the tent I will choose. I've been through all night rains and stayed dry. It's a spacious tent for one person, but slightly tight for two. If it's warm and clear, you can shed the fly and just sleep under the stars with the mesh inner - I've done this in the Grand Canyon. The inner is very effective at preventing midges from getting in. Cost-wise, it runs about $230.
There are a few disadvantages. First, there's the weight: 2060g or 4 lbs 8 ounces. Yes, I know. Second, in heavy rain, the water sometimes pools somewhat on the roof. It still doesn't get in, and it is easily shed by pressing up on the roof once.
So, I like this tent a lot, and have used it under lots of different circumstances. My only reservation for a long walk is the weight, if I'm going solo. To address this, I tried the next tent...
On the T.G.O. Challenge
I had this tent shipped to me from the States. Essentially, it's a single-walled tent with a bathtub floor and mesh screening. I've used it on two Challenges thusfar.
Advantages: This tent is lightweight(!): 900g or 1 pound 13 ounces. It uses your hiking poles in the front and the back, and this contributes to the weight savings. I was caught in a heavy rainstorm in Glen Nevis on the last T.G.O. challenge, and it withstood the rain admirably. It also packs up quite small. Cost-wise, it was $225, which is good value for such a light weight solution.
There are a few trade-offs on this tent. First, I've found that occasionally the back tent pegs come out of whatever ground I've put them in, and the bottom of the tent collapses. This isn't a problem if you can get good purchase with your pegs. Second, I've had condensation inside the tent on several occasions (in moist conditions). If there's a slight breeze, you can keep the front and rear meshes open, and this solves the problem. I'm not sure any single-walled tent can entirely get around this issue.
So, I like this tent, but I think some attention has to be paid on how you pitch it.
Big Agnes Fly Creek UL1
On the Appalachian Trail
This is my newest acquisition, so I can't speak to its T.G.O. performance yet. It a double walled tent, in the sense that there's a mesh inner tent and a separate fly sheet. It also has poles.
My hope is that this tent will strike a balance between Tents #2 and #3 above: light weight (935g or 2 lbs 1 ounce), but with a double skin. The cost was closer to $300/£300, so it's a bit more expensive than the other options I've discussed (and I haven't exactly told my wife about it yet). There's plenty of head room, but the tent is slightly narrow.
The Fly Creek is the tent in the foreground
O.K., these, as I've said, are my opinions. I'd love to hear yours.