A great article at http://www.consumersearch.com/binoculars/types-of-binoculars discusses some of the basics of the types of binoculars one can use for bird watching.

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For general use, experts usually recommend 8x42 binoculars, especially if you don't want to pay more than about $500. You can see more detail with 10X magnification, but unfortunately, any flaws in the optics or design of the binoculars are also magnified. For hunting binoculars or birding binoculars used across big open fields, or for watching ocean birds, it could be worth buying top-quality 10x50 binoculars that cost more. If you want to watch close objects, such as birds at feeders or butterflies, you'll want binoculars that can focus especially close -- a growing trend in binocular technology. For beginning birdwatchers, experts recommend 7x35 binoculars because their wide field of view makes it easier to get the targets in view -- something that takes practice. "Field of view" is a measurement (in feet) of the diameter of the image you'll see 1,000 feet away. A wider field of view means you'll see more of a landscape or sports field without shifting your gaze.
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There are many different brands, and quite a few of them are good. Zeiss is world-renowned for having superior lenses but is fairly pricey (e.g. Zeiss Victory T* FL 8x42), but there are many others in the field at more reasonable prices.

http://www.consumersearch.com/binoculars/best-full-size-binoculars states that the best full-sized binoculars for bird watching are Nikon Monarch ATB 8x42 (available for about $300).

http://www.consumersearch.com/binoculars/mid-size-binoculars suggests the best mid-sized binoculars for bird watching are the Leupold Wind River Katmai 6x32 binoculars (available for about $330).

http://www.consumersearch.com/binoculars/reviews offer some reviews, which among others, recommend the following:

- Leica Ultravid Compact 8x20
- Leica Ultravid Compact 10x25
- Minox HG 8.5x43
- Vortex Razor 8x42
- Nikon Monarch ATB 8x42
- Nikon Action 7x35

There are many other useful links on the above pages which should be explored before choosing the binoculars you buy.

There is no best. A good standard is 7x35 or 7x35 wide angle. These are handy especially for beginning or moderate birders. I generally have preferred 7x50, which capture more light but are heavier to carry and swing around. At the sea shore 10x50 is usually preferred, or even a spotting scope.

If you are asking about brand, I have always found Nikon excellent. You can spend as much as you want on fancier brands if you have the money or less on cheaper ones if you don't. Plan and budget to buy a new pair every few years because the nature of the hobby is that they are going to get beat up over time.