This is a stupid question. All your answers will be by people that like the brand they use. Both brands are good, if you can't make up your own mind on what to buy then you shouldn't be buying.
That's a silly comment. It is not fanboyish to state that ATI has the upper hand right now. Even so I find myself recommending NVIDIA cards on occasion as I have in this very thread because of NVIDIA's extremely aggressive pricing in all segments.
I've had issues with every ATI board and driver I've ever used that I did NOT have with Nvidia.
Yipes, that's a silly comment too. I've had "issues" with every NVIDIA board I've ever owned, but none were deal breakers (well except for the memory management bug on the 320MB 8800GTS) and I loved every single one of them (again except for the 320MB GTS). I would love to hear about some of these issues you've had, but that's a topic for another thread.
The title of this thread is misleading and I wish someone would change it. This is a thread about getting a new mid-range GPU, not debating the merits of our favorite IHV.