Both are legitimate. They win different businesses.
Wix is a hosted product: design freedom for a non-technical owner, zero maintenance, costs that start tiny and grow with usage. WordPress is open software you host: unlimited depth, any plugin, any integration, and a maintenance reality that never fully disappears. The failure mode is not picking the "worse" one; it is picking the one whose exit economics do not match where your business is going.
Wix wins when
The site is marketing plus light commerce, the owner edits it personally, nothing exotic is required (custom data models, complex product logic, heavy integrations), and predictability beats flexibility. A salon, a consultant, a local service business, Wix shipped and maintained for less than a WordPress build costs to quote.
WordPress wins when
Content is the business (publishing at scale, editorial workflow), commerce has real requirements (WooCommerce, product logic, checkout customization), the site must integrate with business systems, SEO is a growth channel you will push hard, or you refuse a monthly ceiling that rises with your own traffic. WordPress is also the portable one: hosts can change; Wix cannot leave Wix.
The math that actually decides it
Wix: small monthly, forever, rising with tiers and apps. WordPress: build cost upfront (higher, a professional one, not a $200 special), then hosting plus maintenance (real: updates, backups, security, the maintenance checklist). The crossover typically lands within 2–4 years for content or commerce businesses, at which point WordPress is cheaper AND you own everything. For brochure sites that never grow, Wix often never loses.
Migration is a known shape
Either direction is doable, Wix → WordPress is routine here, and honest when the reverse is smarter. If you cannot tell which side of the crossover you are on, that is a ten-minute conversation: ask directly or send the brief.