Here is my biased reply: you are better off in Jackson Heights. I have to admit I do not know the exact blocks you mentioned in Crown Heights, but from what I can tell from reading online forums like this one and
Brooklynian.com | Brooklyn Blog and Message Boards :: View topic - crown heights north , Crown Heights (and Prospect Heights) still have quite a bit of street crime - like muggings and beatings.
I used to live in Brooklyn and will always have a soft spot in my heart for it. After I moved to Queens, I still felt that tug. But after being in Jackson Heights for 2+ years, I have to say I'm glad I did not end up in an area of Brooklyn where I would have had to watch my back.
I also really can't compare amenities for you since I don't know that part of Crown Heights, but Jackson Heights has tons of very good grocery/market shopping and lots of great cheap ethnic food of all varieties. Here's a thread on safety in JH
Safety in Jackson Heights - Jackson Heights NY - Queens and if you look around on that forum there are many threads about food shopping etc.
Someone of your demographic I think would feel very very comfortable in Jackson Heights. I don't know about Crown Heights.
If I had to sum it up I would say Crown Heights was a very bad neighborhood that is rapidly gentrifying (more white faces, more new businesses every day) whereas Jackson Heights has always been more of a middle class community (though it had its bad drug/crime days in the '80s like much of NYC) and is changing very gradually - I'm not even sure you could call it gentrifying - because to me that implies an area that is down and out that is suddenly seeing a huge and noticeable influx of money and white people.
The changes that have happened the last two years in JH are more subtle- but there is now a Starbucks, an independent architect-owned cafe, and a very good gallery.
Another point to consider is - do you already have friends in either Brooklyn or Queens? If you do, it might make sense to choose someplace closer to them as travelling between the two is not all that fast or simple.
If you are really interested in Crown Heights you might want to start a new thread as you don't seem to be getting too many replies to this one.