Mongoose for sure. they used to make toys-R-us bikes and now they have some sick frames that not many people notice since they have a bad rep for the bikes they used to make.
This is true. I stopped biking about 3 years ago but just got back into it. Mongoose was shit back then, well not shit but entry level. I'm impressed at the new bikes/frames.
hardrocks are the most underated. i have an 02 hardrock and it is the perfect geometry for a dj bike. right now it is set up as an dh bike with a 24" in the back and Z1 wedges in the front and it rides so nice!
also the p street is set up great for street if you like running 24"s