When you think about core woods, you should ask yourself if you would be comfortable going on a long-awaited back country hunt with a non-fiberglass bow made of the same wood.
With Bamboo, the answer is yes. WIth yew the answer is yes, but with Juniper, the answer is probably "only if I had to."
That being said, I would and have hunted with hickory self bows, but I wouldn't want a Howard Hill bow with a hickory core.
Pick a high-performance core material with a long history of making fantastic bows (with and without fiberglass) and you will not be sorry.