I skied the A3 for about 12 sets and the 2013 prophecy 3 sets. If you made me pick right now, I'd take the A3. I need to give the Prophecy more time. I'm 5'11" and 175-180lbs. I rode a 66" A3 and now have a 67" Prophecy. I think those are the right sizes for you.
I've skied on two different A3's. I really liked the first one, and really disliked the second one. It made me want my S2 back. Because already sold it, I decided to give the Prophecy a try. I only have 3 sets on the Prophecy, and the first didn't really count because of a binding problem, so its way to soon to make a judgement. What I can say, is that I was more comfortable on the A3 in the first 3 sets than I was on the Prophecy. I was running better than my average buoy count on the A3 after 3 sets. I was running about 30% of my 32 off passes (34mph) on my S2, about 70% on the A3. I know I like the Prophecy more than the S2, but it's too soon to tell if I'm going to like it more than the A3. The Prophecy does get me as wide and early as the A3 but I'm not as comfortable in the turns yet. For what it's worth, I haven't even checked the fin settings on it yet.
I should be able to get a few more rides on the Prophecy over the next 4 days.