J Visa Or B1/B2 Visa? WHich One Is Best For Me

Hi, all
I am an IMG from Turkey. I have passed all the USMLEs and planning on applying 2020 match. And I have a position for research beforehand. The university where I am planning to go for research suggests I come on a J1 research visa. But I have read on so many forums that switching from J1 research to J1 clinical may be hard. And I already have a B1/B2 visa on my passport. So what should I do? Should I go on a B1/B2 and ask for an extension of 6 months more and do 1 year of research till I match in 2021 or go on a J1 visa and try to convert to a J1 clinical visa?
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Thanks, Dipaly