I think the system used by F1000 provides an excellent opportunity for exposure. According to their method, all submitted articles are published irrespective of their peer review status or acceptance. Nearly all journals peer review and then issue; while F1000 publish and then peer review. This exposure and transparency in the peer-review and amendment of the submitted article are unique. I think this system may represent the future of peer-review and the cycle of a publication. Read more information about F1000 system:

https://f1000research.com/faqs

PeerJ offers both preprints and peer review publications, but as form of two different submitting processes. They suggest to submit a manuscript as preprint firstly and then when you receive feedbacks from your peers, you can submit a paper with grater chance to pass peer review. While in F1000Research both preprint and peer review are part of the same process, you submit as preprint and than receiving the referee reports. I have good experience with F1000Research. However, it should be mentioned that papers which passed peer-review in F1000Research are indexed in Scopus and Pubmed etc., but not in Web of Science. PeerJ has Impact Factor, and also indexed in Scopus, so if your main objective is improving the visibility, I recommend PeerJ.