I think the common stereotype of a non-premium name tyre being of significantly poorer quality than a premium name tyre is gone now. That might of been the case about 5 to 10 years ago, but manufacturing of tyres has significantly improved in the medium range makes now. Just looking at the moulding of them, the detail and quality now is much better compared to those a number of years ago.
At the moment, for my 4x4 i cant see past Kumho's at the moment. I previously had a set of Dunlop's on the car, and they wore out in no time, and I never really felt they handled well in the wet. They also cost £240 a corner. I've had the named brands such as Pirelli's , Continentals and GoodYears and never really felt that the name got me any noticable performance increase for the price versus a mid-range brand such as Kumho. The only big name I would be prepared to shell out for, but they dont do tyres in the size I need, would be BF Goodrich.
So a good bit of research, some experience of treads that worked well for me, and phoning around i found the exact Kumho tyre I was looking for £110 a corner. Instantly quieter, smoother and most importantly handle considerably better in the wet. Very pleased.
On my old Passat, i bought a set of 18" alloys with a set of tyres. The tyres turned out to be Accelera tyres from india. Never heard of them before, but I have to say that they performed miles and miles better than the named brand tyres I had on the car before. Lots more grip, and much better performance in the wet both in cornering and braking, and they lasted really well. 10k miles later, and there is still a ton of tread left. In fact the rears looked barely worn.
Aside all that name stuff, its worth doing a little research into what your needing from the tyre. There are different tread designs and patterns which are designed to different things. For the 4x4, I wanted a water clearing pattern that would clear water out very well from the tread as I drive in a wet area hitting puddles at speed. Previous tyres which didn't have the V-style tread would often aqua plane and lose grip. Now I'm back on a V-style tread, the issue has gone.
Another thing to look at is the wear rating of a tyre. Its not an exact science, but tyre makers typically attach a wear rating to their tyres, and a number from one brand doesn't exactly equate to that of another. However, for car tyres, when I looked around, they seemed to fall into the camp of:
200ish - a low to mid rating, realistically expect a lower mileage life
400ish - a higher rating - expect a better mileage.
There are so many different types, but i would recommend a mid-range tyre these days. I really dont subscribe to the idea that a premium name brand is worth twice the price of a mid range brand.