When the nature publishing group first introduced scientific reports, there was a lot of comparison between this journal and PLOS ONE. Both had a similar philosophy: "the journal will not reject papers based on their perceived impact"
PLOS even welcomed Nature. Both charged the authors a similar fee and many argued why PLOS one was better than scientific reports. As time has progressed, scientific reports has an impact factor of around 5 now while PLOS ONE has decreased to around 3.5. PLOS ONE publishes roughly 100 papers per day.
The nature publishing group has recently converted Nature communications into a completely open access journal. Therefore, if you want to publish there, you just need to pay $5200, roughly what you will pay a project assistant for a year.