You'll be happy with either mate.
There's often threads like this...
99% of people are happy with their choice of either a spire or a rotor. You'll get some people with problems with their rotor and some with their spire or Prophecy Z2 but these tend to be a minority.
Go with whatever you can get cheapest really. If you go for a rotor however, try to get a 'gen 3' which incorporates a 'shark fin' piece which aids in anti jam as well as velcro straps, which are absent on earlier models. Those gen 1 and 2's aren't bad by any means, but if possible try to get a gen 3.
I also echo Simmershot's advise on play as much as you can and get as good as you can, so grab whatever you can get cheap (recommend the 2nd hand market on here!).