A: Both good, depends on the user.
Both are seriously great website building platforms in my opinion, both with their own quirks, benefits and mind bending irritations.
Both have come a long way over the last few years in terms of integrations, backend access and functionality.
Wix is the only true drag and drop platform, giving you massive flexibility in terms of design and layout. Every element is movable, resizable and deletable. It's kinda nuts.
BUT - with great flexibility also comes great propensity to make things look crappy. In other words, if you don't know what you're doing, it's easy to make a Wix website look bad, thanks to the literally endless possibilities of their amazing drag and drop editor.
This is where Squarespace steps up to the plate.
While it is still technically 'drag and drop', it's more of a block driven setup, similar to Mailchimp and other email marketing platforms. It's less malleable than Wix.
This lack of flexibility though is actually the core of Squarespace's strength.
It ensures that you are going to have decent looking website no matter what you do.
So if you've got time and some design skills, or want to practice your design, Wix is a great option.
But if you just need a great looking website so you can get back to doing what you do best, then Squarespace could be a great option.
And never use Weebly.