All those payment systems have been the subject of hackathons and other security articles. Given the recent news at http://www.techrepublic.com/article/spynote-malware-one-more-reason-to-never-sideload-android-apps/?ftag=CNET anyone that sideloads and uses these Androids for payment are (excuse the bluntness) fools.

I carry the LG G4 as my main phone and if it dies, I'll shop the G5. Samsung lost me over their debacles with tablet registration and KNOX losing a friends phone contents. Good thing they knew "you only lose what you don't backup."

Then again, I'm a big fan of the 99 buck unlocked smart phones. I have a few on my desk "for research." These are found on Amazon.