NORA lighting. Good choice of trims, all of them are individually bagged, and in a box for the 4", or a cardboard wrap for the 6". Quality of the can is decent, I find that if I keep all my purchases to just buying case qty (ie multiples of 6) then all of the cans I get are in good shape. If it's an open box, you get all the ones that have been lying around the warehouse getting beat up! Also, they have a local warehouse (industry, ca) so the rare trims are easy to get.
Price is no object grade:
IRiS (cooper)...these things are very nice. An infinite number of trim options, and all regress the bulb up deep for better looks. Granted, these are only useful on high-end projects, but if you ever have the chance to install them, you're in for a treat. Also, the 5" platform (can) takes many different types of bulbs that you can retrofit after installation- PAR, MR16, AR111, A19, H4, and Flourescent (including dimming). This will prove important here in CA where we have to put flourescent in due to Title 24, but the high end customer wants halogen. Can be retrofitted after inspections are made without much hassle. Not saying it's right, but most people want MR16's and don't care about the power bill so much. http://www.iris-lighting.com/common/index_Iris.cfm