What kind/brand of BMX bike is best?

Oh my....depends on who you're buying it for?  Is it for a girl, boy, adult?  I'm not an expert as far as the bmx circa but I will be happy to give it a shot.  I'm sure you want it to be rugged and able to withstand any jumps and rough terrain.  My first choice would be the Rocky Moutain Edge 20 XC B:

The Rocky Mountain Youth Edge 20 XC combines BMX sizing with theversatility of a mountain bike, giving your grom a solid tool for thetrail. Tough components and rugged 6061 aluminum tubing make this bikestout enough to handle anything that a kid with a new set of wheels candish out.

The Mongoose also seems like a good choice:

Strong and fast, this 20-inch BMX bike by Mongoose is sure to keep upwith any active boy whether he's tackling the trails or cruising aroundthe neighborhood. The Gavel features a sleek, silver alloy frame andtough, 48-spoke alloy wheels that perform reliably, even on wetsurfaces. Other freestyle features include four axle pegs, "knee-saver"handlebars, and an SST handlebar rotor for handlebar spinning trickslike the pros do. The bike's low, step-over height allows for easymounting and dismounting. The alloy brakes and levers provide reliablestopping power, while the alloy pedals are light and provide a largecontact area. A two-tone seat adds to the bike's trim and sportystyling.