I'm new to this board, but I've been riding offroad and dual-sport for 20 years.
Perhaps the best bike that meets your requirements is a KLR650 (the old one, not the new for '07 model). I rode that thing everywhere, including 600 mile days on the pavement, to 300 mile days in the desert sand (this is tough) to 150 mile days on REAL singletrack 6-12" wide! You will want to get an aftermarket shock and re-valve the fork for better performance though. The KLR has an extensive following for adventure touring, and there are some good aftermarket products and a whole bunch of internet sites to research.
I put 20k miles of abusive riding on my old KLR, and at that point, it did need a valve job since the intake valves were very worn. Worn intake valves have been the end of life failure for all my 4-stroke bikes that I've kept long enough to wear out: '86 KLR650, '98 KLX300, '03 KTM450EXC. My theory is that dirt always makes it past the air filter and deposits on the intake valves, tearing them up.
I also had a '94 Honda XR650L, but I didn't like it enough to put more than about 5000 miles on it. This would be my second choice bike to meet your criteria.
I'm gonna thow out the Bimmer, it isn't in the same class as the other bikes.
I'm also gonna throw out the KTM450/525 (even though this is still my primary bike!) The gas mileage is horrible compared to the other bikes, and the vibration is very high. It also doesn't have much frame support out back to support a heavy load when going through the sand whoops. If I was 20 years old though, I might really try to make the KTM work, since it is the most fun to ride, and will allow you to maintain the highest speed off-road. The suspension is awesome offroad compared to the other bikes, and of course it has the lowest weight by far, but getting it to meet the 200 mile range will be very difficult.
I went back and looked at your list and saw the DRZ400S. My brother put a lot of miles on the DRZ400S, and I'd place it at the top of the list if you spend a lot of time on singletrack or if you plan to be picking the bike up off the ground a lot.
KLR vs. XR-L vs. DRZ400S, on your requirements
1. Reliability above all else: They are all excellent in this regard. Have to give the nod to the XR for the easier valve adjustment (threaded adjusters while the KLR and DRZ require shims) and the lack of radiators to bust when you crash.
2. Off-Road performance: DRZ and XR are about tied for the win, but they are not so far ahead of the KLR as you'd think. Stock suspension of the XR and DRZ are decent enough to leave in place, KLR needs a suspension upgrade, but the shorter travel is enough for all but 12" deep ruts. EDIT: all the bikes will be better off with stiffer springs to handle your 3-5 days of camping gear.
3. On-Road safety and handling
Slow, twisty pavement: KLR and DRZ both far exceed the XR! I used to regularly drag the pegs on the KLR! (hey, I'm an ex-roadracer)
Long stretches of highway: KLR wins by far! XR is much more buzzy, gets worse gas mileage, and has less outright horsepower, and the XR even has a narrower power band. That little KLR fairing actually directs the air enough to help reduce neck strain, and since it is frame mounted, it is easy to install a slightly bigger fairing. Then you'll be ready to use the 300+ mile range of that gas tank! The DRZ is a bit underpowered, but it is less buzzy than the XR. All of them have decent brakes, but the KLR is the most underbraked bike in this bunch.
4. 200 mile off-road range: KLR is ready to go. The worst mileage I ever got on that thing was about 33mpg. I didn't have as much time on the XR, but it always had a worse mileage than the KLR, so you'll be hard pressed to get 200 hard off-road miles out of that thing. Fast graded dirt roads will be no problem, but deep sand and some hill climbs will kill the mileage. The gas mileage of the DRZ should exceed the KLR, so just make sure you can get a large enough aftermarket gas tank.
5. Ability to fit bags for 3-5 days of camping. Possibly longer: This will be difficult for any bike, but the KLR and DRZ650 will do the best, followed by the DRZ4 and then lastly the XR.