really depends on what you want to do with them. I've got both. I use xx75 with feathers indoors because i don't need the speed or the range (doesn't get much further away than 20 yards) but i need the to shoot 100 yards outdoors so my arrows are carbons (X10) and they hit with a 36lb shooting barebow. the nearer i come, the tighter the groups but they do tend to be a bit unforgiving so the hand shaking at full draw doesn't help (at 100 yds a 1/2" variance will mean a miss at the other end) but my aluminium arrows won't reach that far anyway. Carbons fly much flatter and faster than aluminiums so i can actually sight on the target and not aim up in the clouds (damn things keep moving which is most unfair).
Step up in easy stages. I started with
ACC, then
ACE and then X10, taking many years to do so but everytime i did the step, my scores improved but arrows, like bows, take a bit of getting used to and need slightly different tuning. My advice? definitely go for ACC (or higher if you can afford them) but don't expect master bowman results immediately.
Good shooting