The mission defines the tool, pick the bike that works best where you will actually be riding. The DRZ/DR series are simple effective tools. The DR favors road vs the DRZ, which favors dirt. Neither is light and neither is particularly low. The 300cc bikes weigh almost as much as the DR/DRZ and offer a lot less power. The KLX250 is so underpowered it was sold the year after we bought it. Nice bike to ride but offroad it couldn't climb over rocks in its path! The DRZ is well-powered, around 325# wet, ready to ride, so not a lightweight machine....but not much heavier than those 300 bikes either.
My wife's KTM 350 EXC-F is about 60# lighter than my DRZ when fueled for the same 325km mission. Neither is great for long highway rides but both do well in dirt. I do know of riders who regularly ride long distance street on their DRZs but I don't think I could on mine.
So, figure out where and what type of riding you want to do and then select the bike