eblightning, first off, stick with 35W HIDs. If you are after maximum light, then I would tell you to stick with 4300K bulbs. If you don't mind a little bit of light loss (still tons brighter than halogens), then you can step up to 5000K or 6000K bulbs.
As for brands, I have installed a few different brands (all bought through E-bay). For the most part, if you buy the $60 kits off of there, you are playing hit and miss. Some have lasted for years, others you can't keep bulbs in them. The big difference I have seen between the kits lasting and not is how the wiring is done. 2 things I will recommend you do to ensure maximum life.
1) Use a relay wiring kit with the HIDs!!!!!! HIDs love more voltage. This is especially true on start-up where they are pulling around 15-20 amps per bulb. I also recommend this as your Expy doesn't have a relay in the headlight circuit, so you are pulling up around 35 amps through the headlight switch for a few moments. While the switch will handle it initially, it won't handle it forever. This is only saving you from problems in the future.
2) Make very good wiring connections!!!!! My personal recommendation is cutting the plugs off of the factory harness and then soldering the wires together as needed. When covering the soldered joints, slip some Raychem-070 over the wiring before soldering. This stuff is shrink tubing on steroids. It is far better than shrink tubing in that 1) it is much thicker and therefore will not easier be rubbed through, 2) has a sealant on the inside of the tubing, so, if you shrink it properly, the wiring will be like the insulation never was cut, 3) this stuff is designed to survive a nuclear reactor blowing up, it will survive under hood conditions very easily (trust me, I work at a nuclear power plant).
Not to pick favorites here, but in my personal vehicle, I installed are no-name HIDs where the box just says "HID" on the box with the hood of an Austin Martin on the box. The other spec I would recommend looking for is "ECE R98". While this is a European standard, for a bulb to be labeled as such, it must meet certain build criteria and beam forming guidelines. It is just a way to rule out the knock-offs compared to a quality bulb system. A lot of guys in my Jag club go through DMMtuning.com. The nice thing with them is that they warrantee the system and if you have anything fail, they will send you new parts. Granted, you are going to pay a little more for this sort of service.
I would also recommend making sure that you get a good seal on the back of the headlight housing. You get water on this bulb and you can run into issues in a heartbeat. In short, when you turn on the HID bulb, it is jolted with 23,000 volts. This is very unforgiving and if you have water, it will tend to short from the positive to the negative, causing the ballast to burn out in a short period of time.
