With most planes, the only benefit of BNF is not having to buy a receiver. Yes, you are paying for the receiver in the price of the plane but it's generally cheaper than buying the plane and then buying the receiver separately. It's not a big difference, but if you like the foamy planes it makes life easier. Some of the micro sized planes have the Spektrum receiver integrated into one unit that has the servos too, so no other receiver can be used.
The DX7 is a good choice, especially if you want BNF ability. It has all the programming that most flyers need, and it is simple enough to learn quickly.