Wix sites ranking OK
Website SEO Hero School created for the WIX contest is not bad ranked. For example http://www.seoheroschool.com/ now ranked higher on request "seo hero" than https://seoheronews.com. Most likely due to links from the site wix.com. However, it is worth noting: the Wix sites are ranked very well, as stated by the representative of Google, expert John Mueller:
WIX websites work fine in search. There are a lot of different setups for new websites. I wouldn't focus too much on a single provider, but rather think about the bigger picture: which will make it easiest for you to maintain your site (adding / changing content)? If you're getting help from others for your site, is there one that they have experience in, which might make it easier / cheaper? Which one offers the features that you think you'll need in the mid-term? There are probably a few options that could work for you, so maybe it makes sense to just try some of them out and see which one works best for you -- websites are websites for Google :).