Fk Konigsports are tried and tested, apparently the Highsports and silverlines have a high failure rate according to Kam Racing, so much so that they stopped selling them. DannyR has had a fair few sets of Konigsports and swears by them. I went for Spax RSX's with the rear coilover setup, not had enough time to drive hard on them but great so far. Ap's are meant to be really good for the money but they don't go very low from what ive read/seen.
Have a look through the thread I had up recently asking basicly the same question, a fair bit to read through on there.