I applied an in-house role with company A (client side). I have been through 4 round of interviews in 8 weeks, feedbacks were all very positive however it required 1 more interview to make decision.
With no guarantee company A would make an offer therefore I accepted an offer (signed & returned employment agreement) from company B, a reputable consultancy with very good compensation package. It starts in 3 weeks.
When I declined company A's further interview request and told them I already accepted an offer from other company. Company A hiring manager emailed me that they were giving me an offer. HR called to discuss compensation details. I have not received any offer paperwork. This only happened on Friday so I will wait until next Monday.
If company A's offer is better than company B, should I accept A and tell B I've changed my mind? Is it unethical? Company A in-house role has more control and better career progression therefore A is better job in long term. Company A, as a client, could potentially hire company B as a consultant.
I would appreciate if anyone could give some suggestion how to deal with this situation.