Its hard to know when to buy, it seems like every year the major brands up grade and they change just a little every year. Best thing to do is see what your hobby shop stock in ways of parts and go with that brand, rather it be losi-mugen-kyosho or whatever. Last thing you want is to be stuck waiting for parts to show up at your door.
As far as what better, wont got there. The answer is each to their own.