The most important factors that influence burning quality are basically three: the disc, the drive firmware and the burning speed.
No drive can transform low quality media into good supports, so the first thing you have to do is use quality discs. With quality discs, basically every drive will give good burnings.
It is quite rare (but it can happen when a drive has been just released in the market) that a drive has a bad firmware so again the most important factor is to choose only quality discs.
Even the best disc if burned at the wrong speed can give bad results. Usually, 16x certified media give best results in most of cases when burned at 12x or 8x. Some very good discs can be burned also at 24x, but in most of cases 8x and 12x are the best choices
I second Kerry's suggestion about the Optiarc 7240, that is an excellent drive, and I agree also that the perfect drive is only a myth