Personally, for editing, I use Acrobat Pro on my Mac at work. For less expensive editing apps on Mac, I'll let others chime in. I've also be using Foxit Reader on Windows. There's a Mac version, but I haven't actually used it and it seems to lack a few features present on the Win version. https://www.foxitsoftware.com/products/pdf-reader/
My point in posting is to suggest that there is absolutely no reason for you to find an "alternative to Acrobat Reader". Reader is free and absolutely the best viewer for PDFs. It is vastly superior to Preview, which only partially supports the wide spectrum of PDF attributes. Keep Reader and add a second app for your editing needs.
In July 2014, the Internet Storm Center reported that the mobile version for iPhone was transmitting unencrypted telemetry and other data to remote servers located in China despite users attempting to opt out of such data collection.