I always go for branded highly rated tyres, just spent £800 on tyres for the 135i, wouldn't skimp on cheap tyres personally. However I have been surprised by some budget brand tyres over the years and very dissaponted with some supposedly 'good' tyres. Take the dunlops I had on the golf for a while, awful grip in wet and noisier than you could believe, constant droning noise at anything over 30mph. They were replaced with vred sessantas which were a good all-round tyre.
I have just removed 2 brand new (400 miles) Goodyear f1 assymetrics from the back of my 135i as they were utter rubbish, made the back end feel floaty and would lose lateral grip far too easily. They have now been replaced with some michelin ps3's and the difference is unbelievable.
So a well rated branded product doesn't mean that they will be great, tyres are a very subjective item to purchase and I think that the average motorist probably couldn't tell the difference between driving on a nangkwank ditchfinder and a semi slick track tyre.
Drove a car with some kwikfit own brand things on once in the wet, it was so bad that anything over 10mph would cause Lethal understeer! I always recommend that people buy the best that they can afford, and if you find that they are not suitable due to noise, ride quality, grip etc... Then go back to the supplier and ask for an alternative as a replacement.