KDan's PDF Reader is actually part of a cross-platform cloud-synced, multi-user sharing system, of which the UWP application for Windows 10 is just a front end. It's worth acknowledging here for its USPs, even though I'll confess that I'd rather have a standalone application (e.g. this and products from the same company) that did everything on the phone and didn't require a subscription to KDan's cloud service (just over £5 a month) to work. Still, full details below if this is something you'd like to play with.

From the Store description:

PDF Reader by Kdan Mobile, one of the world’s most popular PDF reader apps, now officially comes to Universal Windows Platform (UWP)!  PDF Reader not only enables you to read, annotate, and share Adobe Acrobat PDF documents right on your PC, tablets, and smartphones, also provides a brand new freehand drawing and writing experience! With PDF Reader, you can easily manage PDF documents, back up  and share files with your friends, classmates and colleagues via email and cloud storage services. Syncing across all devices and operating systems, PDF Reader is your best choice work with PDF documents anytime, anywhere.

• Fast and stable rendering performance
• Support highlight, underline, strikeout texts, and comments anywhere on the document
• Horizontal/ Vertical scrolling mode
• List/Grid View – Quickly preview PDF pages and jump to the specific page
• Open password-protected PDF files
• File Search

• Choose night mode or reading mode to adjust the screen to fit your reading environments
• Manage bookmark, outline, thumbnail, and annotation with ease

• Import PDF files from device folders
• Share PDF files via the sharing feature
• Send out PDFs as email attachments
• Print out PDF documents

• Work well on any device and screen 
• Draw and doodle on your documents, with the color of your choosing
• Call up a digital ruler to draw straight lines

• Sync and access your documents across devices and operating systems
• Send download links to share files easily
• Sign up and verify your account to get 500 MB of free space

• Convert and fax files online with purchase of credits

I think that if your life (or work) revolved around PDF files then this might be a good solution to investigate. For the casual user, opening a PDF document once a month, this is all way over the top. Still, here are some of the promotional screenshots, giving a flavour of 'PDF Reader - View, Edit, Share' in action:

Documents can be opened from local device or KDan's cloud drive - conversions cost credits though, and these need recharging every now and then with real money. It's not clear whether these are included with the quarterly subscription or not.

Viewing and editing is where the application shines, with complete control over appearance and a barrage of annotation tools.

Managing PDF documents in the KDan cloud drive and (right) showing off the dark theme - very useful.

You can download the PDF Reader front-end here in the Store. I did try it briefly, but the reliance on a paid cloud account just to open up a small PDF file on the phone seemed over the top to me. Still, this may be just the ticket for businesses?