Seems like you have set your mind on Lonza (if offered), and either way has pros and cons.

Just curious, what's the travel time like between your home and Lonza vs Astar? Because I think travelling time should be put into consideration as well.

As to stalling the signing of contract, sorry I have no advise on that. I've read that after signing, if you do not show up on the 1st day, you are by right still not bonded by the contract. Not sure how accurate this is but nonetheless, I don't think you would want to try it.