Just adding my twopence ha'penny worth, mainly in confirmation of what's already been said.
I bought a Vango Force 10 Helium 2 for multi-day treks, having had a Vango Banshee 300 for many years. The latter is just too heavy to lug about (2.65 kg).
I bought it after a lot of research, and it seemed to offer the best compromise between weight and price (1.33kg, £160-ish). If you take your time, you can usually find a good deal.
I've used it a fair bit, and really only have 2 criticisms of it:
1. it flaps in the wind, however tightly you set it, even on flat ground.
2. it's very difficult (= impossible for me) to get it set tightly on uneven ground, and it's clear that this is really due to the single end-post design: the tent fabric just doesn't like this geometry.
I set it up last weekend against the new Alpkit Tetri my son had bought, and, to my surprise, the amount of space available - floor area and height - seemed very comparable. The difference is that his tent weighs 3 kg! Having said that, it does look as if it would stand up to high winds better, and I've never tried either the Banshee or the Helium in really high winds (which, to be fair, they're not designed for).
I would second the view that it's worth getting a 2-man tent for solo expeditions. The extra room - a lot! - comes at a weight penalty of less than 150gm (in the case of the Helium), which is barely a mug of water.
I get a fair bit of condensation in both the tents, notwithstanding vents built into the flysheet; but I suspect this is unavoidable with the materials used for tents these days, which all seem to be more or less the same. I typically get some underneath the mattress also inside the tent, but I don't think it's a groundsheet issue - I've camped in some pretty damp places.
As regards waterproofness, I've had no issues with either - even in heavy rain.
One thing I like about both tents is that they can be pitched with the inner and flysheet fixed together, which is what I inevitably do; and this is pretty handy when it's raining.
Whatever you go for, I hope it works for you, and you don't have an experience like nick70.
Finally, this blog gives a reasonable review of the Helium.
https://www.hikersblog.co.uk/force-ten-helium-100-tent-gear-review/