Urgent, Help! Quest about H1B Transfer

Working at A university(H1B). Got an offer from B university, B has filed a transfer for me but I got another offer from C university which is much better than B (tile, research field....is the same with A, I-140 NIW pending), what should I do?

1)Do not care B, Ask C file another H1B transfer?
2)which one would be effective if both transfer are approved or doesn't matter?

Please help!

Thanks