Qantas first class, no contest. I have never flown first on either, but did fly coach on HA HNL-SYD there and back a few years ago and it was probably the worst airline I have ever been on in terms of service/organization, plane niceness and overall experience. Everyone always says how nice Qantas is.

I always compare the downside of booking and not booking. If you definitely know you are going and have the miles and definitely want first class, then there is no downside to booking. If you decide to change dates and not change carrier, but still go within the next year, there is no fee to change on AA. I generally prefer to just secure seats in such a situation, good availability or bad. Worst case scenario, you will be stuck with the dates u have and not be able to change, but if flights are not available on those dates later on anyway when you decide you want to book, you're stuck with no flight options. This is all if you have enough AA miles that you don't need to use anywhere else before then.