困難的決定 - offer

Dear All,
It is much easier to me to describe my situation in English. So, please kindly take a moment . Any suggestion is appreciated.

I have recently graduated with my PhD degree in Chemical Engineering. I got a job offer (for being a Process Development Scientist in upstream bioprocess development) from a company (company A) in Missouri. My starting date is the end of July. It is mainly about cell culture process design, development and scale up. I have experiences in this field at least 6 years (academic and industry). So, the job responsibility is not difficult to me. In order to look for other opportunities, I have asked to extend
my starting date from the end of June to end of July.

Recently, I completed two on-site interviews with other company (Company B in Maryland, near D.C. and Company C in NJ, near Princeton). Both jobs are about working as process development scientist regarding downstream process development (protein primary recovery and chromatography steps). I only have about 1-2 years experiences on this field and I really want to expand my expertise in this field. However, company B and C need about 3 weeks for making their decision. That means I have to make a decision
between A or B/C.

Here is the comparison between A, B and C:
Company Size: same
Future of company: B, C >A
Locations: B, C > A.
Cost of living: C>B>>A
Possibility for growth: C, B > A
Difficulties of job: C, B > A
H1B sponsorship: same

So, what do you think about my situation?
1) Should I decline the offer from company A? Then wait for the decision from company B and C? In this case, I would worry about the negative answer from company B and C. Then I have to spend another couple weeks to find a job.
2) Should I start my job in company A? Then transfer to company B or C if they offer me position. In this case, I would worry about it is a bad impression to company A and to my reputation. Since Company A is a big company.
3) What would you do?

Thank you all for your time on this.


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