MBP13" eGPU - Help Choosing

Hello!
I've been looking into getting an eGPU for my MBP13" 2017 (maxed out). The new BM eGPU makes that decision harder!

I was looking at a Sonnet 350w with either a Radeon RX580 or a WX5100. Both these options would come out to around $550 / $650 respectively (maybe less if I can get the Sonnet on eBay). Which of those cards would you recommend for FCPX use? Is there a big difference between the two? How would imagine they compare with the new BM (based on specs since it's not out yet)?

Thanks!

Seems to me that the BM and RX580 are very close. I find it interesting that GPU manufacturers give specs, but only the ones they excel at, and not all of them, and refer to some by different names. But looking at tech specs I can find, these two look very close the giving the same potential performance. But I'm not eGPU expert, just reading tech specs.