I am a little lost as to what you mean by "best focal point lens brand?"
Your budget is tight for everything you want, but you can do it... Is it going to be the top of the line? no, but you can get pretty darned good.
You didn't mention zoom range you need. Guessing by your camera I am going with mid range.
The ideal would be the Nikon 24-70 f/2.8 but that's about 3.5x your budget, so...
Tamron makes a 28-75mm f/2.8 that is pretty well loved and reviewed for being sharp and good quality. Tamron also makes a 17-50 f/2.8 in your budget range.
I own both lenses. I prefer the 28-75 on a crop sensor for several reasons: first being if you are going to upgrade ever to full frame it will carry with you and the 17-50 won't.
Second: the 17mm end of it is NOT good in portraits of one person. At the 17mm end of it you are getting into fisheye distortion with the lens and that will make for big noses and bent lines. I get into trouble with it all of the time at the wide end because I am not paying close attention to it when I am shooting. It can be fixed in processing, but that's MORE time on the computer and a pain in the butt.
Third the 28-75 seems a bit sharper than the 17-50 to me. Both produce great results, but if you are being nit pickety and looking at your images LARGE and in detail? the 28-75 shows better.
Overall my first choice (obviously) is the 28-75 f/2.8 within your budget. If you are looking for a wider range of zoom you aren't going to find it at f/2.8 AND in your budget. You may be able to find one of the older Sigma 24-70 f/2.8's used in your budget. I wasn't sold on the older version of it. When I bought my 28-75 back when I tested both out in the store and chose the Tamron for quality and sharpness. The newer version is pretty awesome or so I hear, but definitely out of your budget.