Yes it is highly preferable for mergers/acquisitions/financing because the law is well established and widely known in those industries.

If you run into some legal question somewhere down the line, investors and their lawyers will be much more comfortable with Delaware law than some other state who may not have clear language on the books and/or have never tested that particular situation in court before.

That is really a wild thing. I culture of legal belief based on precedent. It's as if one is joining a club that has rules of business conduct clearly documented.