Wouldyou build a website for a major brand using wix?
depends on, Can you Code
Yes :- then its about which language or framework you know and prefer to built
No:- then probably you have to go for this, remember Coding Will be tough at start but will make things easier eventually because you wont be relying on any third party website to build your stuff for you, unless you are a entrepreneur with shit ton of money usually that is a bad choice to build websites for major brands, I might be wrong tho, but this is my opinion.
PS:- I have around 6 years of exp in TECH and I work in ECOM Mobile Apps development for Major Retailer(GAP INC) so I gave a technical opinion.