I just want to know which website is more useful for seo point of view in between Complete html based site vs CMS based site ?
Well, a site with a CMS is also based on HTML, CSS plus PHP etc. Don’t think there would be much of a difference in terms of SEO if you use CMS or not. I’d rather have a look at creating great, frequently updated content for your site, having other high-quality sites link back to your site, use things like ALT tags and write your website content in a people-friendly way, while still integrating certain search terms. But I still believe the by far the most important thing is having valuable, useful, up to date content on your site that’s relevant to your target audience!
…Plus the Webflow CMS and page settings are built so you can set dynamic data for SEO and sharing:
From an SEO’s perspective I would use pages and save the CMS for other things such as blogs, reviews and team sections. The reason for this boils down to the fact that you can only add title tags to anchor texts within pages not within the CMS. The CMS also only allows for one alt tag for all images within a collection item. These maybe small to some but in SEO all small things add up to something bigger. Title tags on anchor text and alt tags on images is standard SEO practice.
I would love to use the CMS but have found that it is impracticable in its current state for SEO page purposes.
Hope it helps.