Those of you who have some experience behind you with Biblical languages ...would you have preferred to learn one before the other?
In other words, do you see a significant advantage in learning Hebrew before Greek? Or the inverse?
I took one semester of Ancient Greek (which isn't biblical Koine Greek, but at least it helps a bit) in college. I found it very difficult and didn't do well in the class, so I didn't continue with the second semester. Also it was long enough ago that I'd forgotten nearly all of it by the time I got to seminary many years later. I was loving getting to know the Old Testament better, since I'd found much of my Christian experience had focused more on the New Testament. For that reason, and the fact that I'd already had a wee bit of Greek and wanted to try something different, I chose to go with Hebrew first. I loved it and totally threw myself into it. Having a good teacher helped. But I just loved the concreteness of the vocabulary, the beauty of the script, etc. Sure, it was hard too, but I did much better this time around.
One of my professors told us that in order to study the New Testament and Greek well you need to know the Old Testament and Hebrew. I think you could still work on them in either order if you're planning to do both. Some people find it easier to start with Greek, because at least the letters and some of the vocabulary and grammar are somewhat familiar from English or from having studied another foreign language. Hebrew is so different! But the other way to look at it is if you study Hebrew first, you are taking on the harder language first so it can only get easier after that. Actually in some ways Hebrew is easier than Greek. The grammar is simpler; there are not so many cases to memorize. But I've never gone on to study Greek after my aborted attempt in college. I might find it easier now that I've been exposed to it so much through Logos.
Someone has said that learning a language is 60% motivation and 40% memorization and skill training. I found it very motivating for me to constantly keep in focus that of all the languages God could have chosen to have His authors use, He chose Greek and Hebrew. If they were important for God, then I could trust Him to help me learn them. Still was a lot of hard work, but at least the motivation was there.
The differences between Greek and Hebrew are such that you can't build on one to learn the other. But if you struggle with learning languages, you'd be better off with Greek first, IMO. Greek generally considered to be easier to those who struggle, as its alphabet is relatively simple, its grammar closer to English, and several English words have their roots in Greek. None of those things are true of Hebrew. Therefore whilst you become skilled at the discipline of learning a language, you're less likely to give up Greek than you are Hebrew.
Part of the answer for this question comes from the quality of the teacher. I know that Greek would be my preferred first language, and it was; I also know that I enjoyed my Hebrew class more than my Greek class. The teacher was a native Hebrew teacher and thus made the class personal, not just academic. I suppose that a Greek teacher could do the same - mine didn't.
I've had a lot more Greek than Hebrew (Greek was my minor in college and I didn't have any Hebrew until seminary) so I'm sure that influences my thinking, but I think Greek is easier. I also find that I use it far more 25-30 years later than i do my Hebrew.