i.e. I've some AMP-Pages
amp-index.html
amp-subpage1.html
amp-subpage2.html
amp-subpage3.html
should I link from amp-index.html directly to the amp-subpages or is it better to link to the non-amp-pages?
i.e. I've some AMP-Pages
amp-index.html
amp-subpage1.html
amp-subpage2.html
amp-subpage3.html
should I link from amp-index.html directly to the amp-subpages or is it better to link to the non-amp-pages?
It is up to you because in AMP documentation there is no rule for this situation or no restriction, You can link AMP page to another AMP page for fast execution.
According to AMP documentation if you have only one AMP page than your amp and non amp url is same. For more detail Make your page discoverable
According to my point of view you can link AMP-Page to AMP-Page for fast execution.
It completely depends on you how fast you want to execute your page and how efficiently you want to show your content to the user.
If you like to see the variation between the content representation in AMP vs Normal version you can refer to the following links: http://akashshivanand.com/google-news/google-mobile-search-ui-redesign/amp/ and http://akashshivanand.com/google-news/google-mobile-search-ui-redesign/
Conclusion
AMP version if Content and the execution speed (in some cases) matters a lot for you.Non-AMP version if design and functionalities matter a lot for you.Have a great day Ahead!!
Other than speed it has SEO benefits as well. AMP pages will rank better than normal pages on mobile.