RE: Opinions
Negative and positive shift are two methods to cause a "pulse" of a given time duration that is sent from the transmitter to the receiver. The length of this pulse tells the receiver where in the servos travel it should be placed. The point is that there has to be a detectable shift for a pulse to occur. What's really important here in the US is that Hitec and Futaba are compatible between their transmitters and receivers becuase they are negative shift. Airtronics and JR are compatible because they are positive shift. It's been reported here on RCU that the rest of the world is positive shift... Most receiver manufacturers sell JR/Airtronics and Futaba/Hitec shift receivers. Hitec also makes JR/Airtronics receivers... So depending upon the transmitter you have you'll need to know what shift receiver to buy.
Since you don't have a bunch of old receivers that you want to re-use then I strongly recommend the Futaba 9C. It is IMHO the best "bang for your buck" transmitter available. If you do some searching here on RCU you will find a great deal of information about the 9C, JR 8103, Hitec Eclipse, Multiplex, etc...
In my Edge I am using Hitec HS-5945MG digital servos. So far their performance has been outstanding!